The Stolen Earth (TV story)

The Stolen Earth was the twelfth episode of series 4 of Doctor Who.

The episode marks the first television appearance of Davros since the 1988 story Remembrance of the Daleks. The result of Dalek Caan's emergency escape in Evolution of the Daleks is revealed as well.

It also marked the return of several past associates and companions of the Doctor, including Sarah Jane Smith, Martha Jones, Jack Harkness, Harriet Jones and Rose Tyler. It served as a "cross-over" between Doctor Who and its two current spin-off series, marking the first appearance in the series itself of several characters introduced in those spin-offs; namely, Ianto Jones and Gwen Cooper from Torchwood; and Mr Smith along with Luke Smith from The Sarah Jane Adventures. The episode also featured the "death" of Harriet Jones and the loss of the Valiant in ill-fated meetings with the Daleks.

Once again, it showed the legacy that the Doctor leaves behind on Earth, with many of his ex-companions and allies playing a very important part in saving the world.

This episode's cliffhanger, which featured the Tenth Doctor beginning a regeneration, caused much commotion within the circles of Doctor Who enthusiasts, who were taken by surprise. No announcement was made regarding actor David Tennant's departure, which triggered a phenomenal influx of viewers during the Series 4 finale, Journey's End, in anticipation of a new incarnation of the Doctor and new respective actor. However, this flurry of suspense would be dispelled with the outcome of the finale. Narratively, it also paved the way for the Doctor's "final" regeneration of his original cycle as revealed in The Time of the Doctor.

Synopsis
When Earth and twenty-six other planets are stolen and taken to the Medusa Cascade and the Doctor is nowhere in sight, it's up to the combined forces of UNIT, Torchwood, Sarah-Jane and Rose to fight off the thieves, who only have one thing to say to the resistance: "EX-TER-MIN-ATE!"

Plot
Having seen the signs, the Tenth Doctor and Donna return to Earth to find everything in order. The Doctor asks a milkman what day it is — it is Saturday. Donna presses the Doctor for an explanation of Rose's unexpected reappearance, and the Doctor explains that if Rose can cross from her parallel world to Donna's parallel world, then the walls of reality are breaking down. Still, with Earth apparently safe for now, they return to the TARDIS. Once they enter, the Earth begins to tremble. Inside the TARDIS, Donna gets the Doctor to admit that despite the danger of whatever's coming, he's still happy about the prospect of seeing Rose again. Suddenly the TARDIS is hit with a violent jolt. The Doctor and Donna rush to the doors and fling them open to find they are hanging in space. The Doctor checks the readings to find out why they've moved... only to learn they haven't. Their position is fixed and the TARDIS is still in the same spot it landed in, it is the Earth that has disappeared. Impossibly, the entire planet has been stolen — but by whom?

At the UNIT New York Base, Dr Martha Jones regains consciousness after an earthquake to find UNIT in chaos and its personnel panicking. One horrified colleague tells Martha to look at the sky.

In Torchwood Three, Captain Jack Harkness guesses that the Rift may have been responsible for the brief but violent earthquake that has just devastated the Hub. After making sure that the other members of Torchwood Three — Gwen Cooper and Ianto Jones — are all right, Jack heads outside to survey the damage. Presuming it to be a localised event, Ianto and Gwen look at the computers. Ianto realises that whatever the problem is, "It's a bit bigger than South Wales."

At 13 Bannerman Road, Ealing, London, Sarah Jane Smith and her son Luke comment on the earthquake and wonder why it is now dark outside since it was only 8 a.m. when the quake struck. Sarah Jane asks her alien supercomputer Mr Smith for an explanation. Mr Smith says that she should look outside because she will "find the visual evidence most conclusive".

In Chiswick, London, Donna's mother Sylvia and grandfather Wilf are not sure what has caused the earthquake, but Wilf is positive it's aliens again. As they step outside their home, Sylvia looks at the sky in horror.

On the street in London where the TARDIS had been parked, the milkman turns and sees Rose Tyler materialise in a flash of white light, carrying a large futuristic gun. She looks up. Alone of the Doctor's friends, she is not surprised. Arming her gun, she declares, "All right, now we're in trouble. And it's only just beginning."

The familiar sky is gone. The sun is gone. The constellations have been replaced with strange new ones. Twenty-six new planets have appeared in the sky.

Aboard the TARDIS, Donna demands to know if her family is dead. The Doctor does not know. He decides they need help, and he sets course for the Shadow Proclamation.

At Sarah Jane's house, Mr Smith picks up readings of a fleet of two hundred spaceships apparently headed towards Earth. Luke also lets Sarah Jane know that Maria and her dad are in Cornwall and that he told them to stay indoors; and Clyde is inside with his mum.

At UNIT, American UNIT leader General Sanchez enters and tells all soldiers and staff that Geneva has declared a Code Red Emergency. Martha tells him that she has tried to phone the Doctor, but the signal is dead. The number calls anywhere in the universe, but the signal is being blocked by some unknown force. Sanchez notes that they will likely find out soon: the fleet is coming into orbit.

Gwen calls her husband, Rhys, and tells him to stay indoors and call her mother. She then joins the others as they are reviewing the situation. The atmosphere is in place. They muse that whoever has done this wants the human race alive, which Ianto calls "a plus". Gwen notices something at the heart of the planets that gives a different reading. It is not a planet.

Meanwhile, Rose is walking along the streets of London, which are in chaos with drunks, looters and hysterics. She threatens a pair of looters with her gun (who promptly scarper) and looks at a computer screen in the electronics shop they were robbing. It shows a readout of the alien ships.

Torchwood has also detected the ships coming into orbit. Jack's phone then rings. It is Martha calling, and they confirm that neither of them has heard from the Doctor. They discuss UNIT's "Project Indigo", which is the reason for Martha Jones's presence in New York. Mr Smith tells Sarah that the ships have a message for the human race and puts it through. It consists of a single repeated word: "Exterminate!". The message is heard on all frequencies, including UNIT, the speakers at Torchwood Three, and at Sarah Jane's attic. Jack and Sarah Jane react with horror as they realise the enemy is the Daleks. Jack says, "I'm sorry, we're dead", kissing Ianto and Gwen on the forehead. Sarah hugs Luke, crying, "You're so young."

Rose hears the message and heads outside to see a massive Dalek spaceship flying over London, shooting at everything in its path. In space, thousands of other saucers descend upon the helpless Earth. At UNIT's New York City base, General Sanchez orders everyone to their battle stations and Geneva declares an Ultimate Code Red: put simply, Earth is at war. The room promptly shakes and Martha rushes to the window in time to see dozens of Dalek ships descend and wreak havoc and destruction upon Manhattan. Aboard a massive spaceship at the heart of the cluster of planets, the Daleks finalise their plans. The Supreme Dalek, a red Dalek with extra panels, declares that the Crucible will soon be complete and "We have waited long for this ultimate destiny. Now the Daleks are the masters of Earth!". The Daleks eagerly take up the chant.

Far across the universe, on board the TARDIS and unaware of the unfolding destruction on Earth, the Doctor and Donna arrive at the Shadow Proclamation. They are greeted at gunpoint by its rhino-headed guards, the Judoon, but the Doctor convinces them they mean no harm and need help with the trusted help of his knowledge of the Judoon's language. A female member of the Proclamation tells the Doctor that the situation is worse than he suspects — not one but twenty-four planets have been stolen. Donna asks about Pyrovillia, but the Judoon captain tells her that Pyrovillia is a cold case; it disappeared over two thousand years ago. Donna asks about the Adipose Breeding Planet and the Doctor realises that planets are being snatched out of time as well as space. The Doctor heads over to the computer and shifts the display of the missing planets into 3D. He adds Adipose 3, Pyrovillia, and the lost moon of Poosh, which all vanished in the past. The model rearranges itself into a perfect balance, fitting together "like pieces of an engine". Recalling a distant memory of his, the Doctor begins to realise who is responsible as he says that someone tried to move the Earth once before...

Back on Earth, the Daleks attack the Valiant, disabling its shields and forcing the crew to abandon ship. Jack, Gwen, and Ianto try to find a way to stop them, but their efforts are futile. Daleks are landing in Japan, the Air Force is put into retreat over Africa, and contact with the British Prime Minister's plane is lost. Back in Manhattan, the UNIT base is attacked by Daleks. Jack tells Martha to get out of there, but she does not listen. General Sanchez declares that Project Indigo has been activated. Back in the control room, personnel cowering behind desks are knocked backwards as Daleks blast their way into the room. UNIT soldiers fruitlessly but bravely open fire as administrative personnel attempt to flee, though some are exterminated in the process. Sanchez leads Martha and another UNIT soldier to the vault where Project Indigo is being kept. He orders Martha to put it on, and she straps a device onto her back. As Jack protests for Martha not to use it because it is too dangerous, General Sanchez orders Martha to do it. He hands her something called "the Osterhagen Key". Martha is horrified, understanding the purpose of the key. She at first refuses to take it, but General Sanchez orders her to do so for the sake of humanity. Martha activates Project Indigo as Jack rages. The General and another soldier begin firing as the Daleks break in, and Martha vanishes.

Inside Torchwood, Jack tells Gwen and Ianto that Project Indigo is a teleport device reverse-engineered from the teleport pod salvaged from the Sontarans, but they have no coordinates or stabilisation. When Gwen asks where Martha is, an upset Jack says she has been "scattered into atoms. Martha is down."

On board the Dalek station, the Supreme Dalek orders the Daleks to prepare landings and bring the humans to "the Crucible". He receives a call from the control room, asking for any news. The Supreme Dalek declares, "Earth has been subjugated." The speaker is a sinister figure: the lower half of his body is Dalek, but his upper half is hidden in shadow. However, a blue light is visible on what seems to be his head. He is really asking for news of the Doctor. The Supreme Dalek gleefully replies, "No reports of the Time Lord. We are beyond the Doctor's reach!" The figure is fascinated by the Dalek's triumphant tone and warns him about his pride. Undeterred, the Supreme Dalek proclaims, "The Doctor cannot stop us!" The figure replies, "And yet, Dalek Caan is uneasy." A light switches on to show a Dalek with its shell opened to reveal the mutated, tentacled creature inside, its top half destroyed. The Supreme Dalek protests, "The abomination is insane!" The figure demands that the Dalek show respect; after all, without Dalek Caan, Earth could never be conquered. Also, everything Caan says comes true. Caan says, "He is coming. The three-fold man, he dances in the lonely places...oh, creator of us all...the Doctor is coming!" then bursts into insane laughter.

Back at the Shadow Proclamation's space station, Donna is sitting on the stairs, waiting for the Doctor to work out what has happened. A member of the Shadow Architect's race comes over and gives Donna some water. She somehow knows that there had been something on Donna's back earlier, and tells her there is a loss still to come. The Doctor asks Donna if anything strange was happening on Earth. Donna reminds him about the bees disappearing. The Doctor realises that this is a clue. Donna tells him some people thought it was pollution or global warming, but the Doctor tells her that, in fact, the bees were returning home, to the planet Melissa Majoria: the Tandocca Scale. They realise that if they follow the trail, they can find the Earth. The Shadow Architect stops them, saying, "The planets were taken with hostile intent. We are declaring war, Doctor, right across the universe, and you will lead us into battle!" The Doctor looks stunned, then replies, "Right, 'course I will. I'll just go get you a key." He closes the door and the TARDIS dematerialises, to the Shadow Architect's fury.

Back on Earth, the Daleks have enslaved London and are ordering all humans to leave their homes. Wilf and Sylvia watch. When a man and his family defy the Daleks and run back inside their house, the Daleks brutally incinerate the building, leaving no survivors. Wilf and Sylvia run onto the street and are confronted by a Dalek. Wilf grabs a paintball gun and shoots the Dalek in the eye, but the Dalek melts the paint away — declaring "My vision is not impaired!" The Dalek prepares to exterminate them, but then explodes. Behind its wreckage stands Rose, who has blasted it with her gun. She asks if they are Donna's family, and when they reply yes, she tells them she needs them. Wilf reveals he has tried calling Donna, but there is no reply. The last time Donna had phoned them was when she was on Midnight. Sylvia thinks this is ridiculous, but Wilf tells her she cannot start denying things now. Upon discovering that they do not know how to reach Donna, Rose despairs; they had been her "last hope" to find the Doctor.

Meanwhile, the TARDIS stops in the Medusa Cascade. The Doctor tells Donna he came here when he was just a kid (ninety years old) and that it is the centre of a rift in time and space. Donna asks about the twenty-seven planets. The Doctor tells her that they are nowhere. Donna asks what they are to do, but the Doctor does not reply... he now has no options and no clue what to do next.

On Earth, Torchwood and Bannerman Road listen as the United Nations officially declares Earth's surrender. Sarah and Captain Jack have given up: Earth has no hope but to wait and pray that the Daleks bring the end quickly. At the Nobles' house, the laptop suddenly switches itself on and a voice comes through. Sarah and the people at Torchwood hear it, too. Jack believes it is just another suffering person crying for help amongst millions of others. He tells Gwen to leave it, but the woman speaking shames him and demands that he stand to attention. She identifies herself as Harriet Jones, former prime minister. Harriet also makes contact with Sarah and decides they should be able to talk to each other. There are four contacts: Harriet, Sarah Jane, and the Torchwood team, but the fourth contact is having trouble getting through. Rose assumes she is the fourth contact, however, the Nobles' lack webcam, Sylvia having forbidden them, believing webcams to be "naughty". To Rose's surprise and dismay, Martha appears on screen as the fourth contact instead. Feeling left out, Rose protests, "Who's she?", but no one in the network can hear her. Martha reveals that Project Indigo had brought her home to her mother, possibly tapping into her mind to determine where she really wanted to go. Harriet introduces Torchwood to Sarah. Jack states that he has been following Sarah's work, telling her, "Nice job with the Slitheen." Sarah tartly replies that she has been staying away from Torchwood — "Too many guns." Far from offended, Jack suggestively tells her that she is "looking good". Harriet is unimpressed by Jack's incorrigible flirting, though Sarah is quite flattered, and explains that they are communicating through a subwave network — a sentient computer programme obtained from the Mr Copper Foundation to contact anyone and everyone who can contact the Doctor. Jack tells everyone that what they need at the moment is something to fight the Daleks with and asks Martha what the Osterhagen Key does. Harriet abruptly interrupts telling Jack that the Osterhagen Key is not an option and isn't to be used under any circumstances and what they need is the Doctor. Sarah wonders why Harriet is doing this, given that the Doctor deposed her. Harriet admits that she has often wondered whether or not her decision was wrong. Regardless, she asserts, "I stand by my actions to this day because I knew that one day, the Earth would be in danger, and the Doctor would fail to appear."

Martha explains that she has tried to phone the Doctor, but the signal cannot get through. Jack realises they can transmit to the Doctor using "all the power of the Rift". Luke points out that Mr Smith can tap into the global telecommunications network, forcing every phone across the globe to call the same number at the same time; Jack is impressed. Ianto appears beside Jack and theorises that as soon as transmitting begins, the subwave network will become visible to the Daleks. Harriet understands that the signal will be traced back to her, but she declares, "My life does not matter — not if it saves the Earth." Jack salutes her. She tells Jack to give the Doctor a message: "He chose his companions well." Martha sends them all the number of the phone Martha gave to him number and Rose decides to call the Doctor herself.

The transmitting starts, manifesting as glowing blue rings that shoot up the water tower in Roald Dahl Plass and extend out into space, Earth and the twenty-six other worlds calling their Doctor for help. Rose, Sylvia and Wilf start to call the Doctor. Mr Smith and the equipment at Torchwood are pushed beyond their limits. Suddenly, transmitting slows. The Daleks have detected the subwave network. The Supreme Dalek orders that the culprit be exterminated. The figure in the control room contacts him again, telling him, "I warned you, Supreme One. Just as Dalek Caan foretold, the Children of Time are moving against us, but everything is falling into place." Gwen warns Harriet that the Daleks have found her, but Harriet keeps working. She sends control to Torchwood just as the Daleks arrive in her home. She introduces herself as usual, and the Daleks tell her they know her. Harriet retorts defiantly, "Oh, you know nothing of any human. And that will be your downfall." With this, she is exterminated, though the Daleks have the decency to destroy the video link before doing so.

On board the TARDIS, as the Doctor and Donna sit despondently, the phone Martha gave him starts ringing. The two jump into action and, although there is no voice on the other end, the Doctor picks up the signal and locks onto it. The TARDIS travels through time, overloading. The twenty-seven planets come into view and the Doctor realises that they were all one second out of sync with the universe — he describes it as "the perfect hiding place". He picks up the subwave network and his companions appear onscreen. The Doctor introduces Donna to all of them but is disappointed that Rose is not visible.

On board the Crucible, Caan says, "He is here...the Dark Lord is coming." The figure demands access to the subwave network.

Suddenly, all the contacts vanish off of the screen. Donna thinks they are losing contact, but the Doctor realises there is another contact coming through. He thinks it is Rose, but when he and Sarah hear the figure sneer, "Your voice is different and yet, its arrogance is unchanged," they realise who it is with horror: the creator of the Daleks, Davros. He gloats, "Welcome to my new empire, Doctor. It is only fitting that you should witness the resurrection and the triumph of Davros, lord and creator of the Dalek race." The Doctor protests that Davros was destroyed in the very first year of the Time War, that his command ship flew into the jaws of the Nightmare Child at the Gates of Elysium, even though he tried to save Davros. Davros mockingly replies, "But it took one stronger than you — Dalek Caan himself." Caan continues the story, shrilly crying, "I flew into the wild, and the fire; I danced and died a thousand times." Davros explains that after following his escape from New York, Caan's emergency temporal shift took him back into the Time War.

The Doctor protests that the war is time-locked, and therefore completely prevented from being accessed. Davros points out the obvious: "Yet he succeeded." Caan was somehow able to break the barriers and rescue Davros, but in the process lost his sanity. The Doctor realises that after being rescued, Davros created a new race of Daleks. Davros boasts, "I gave myself to them — quite literally: each one grown from a cell of my own body." He reveals that parts of his torso have been replaced by metal — much of his ribcage and what lies beyond is clearly visible. He proudly proclaims, "New Daleks...true Daleks. I have my children, Doctor. What do you have now?" The Doctor's response is just one word: "Bye!" He cuts transmission with Davros and sets the TARDIS for Earth. The Supreme Dalek orders that the Daleks locate the TARDIS and the Doctor, but Davros points out that they need only look on Earth; the Doctor is sure to seek out his companions. Caan ominously screeches, "Death is coming. I can see it! Everlasting death for the most faithful companion!" Suddenly, the Daleks detect that the subwave network has been rebooted and the new location is Torchwood. The Supreme Dalek orders Torchwood exterminated.

On Earth, Jack contacts Martha by phone and asks what the two oscillating digits on the Project Indigo transporter are; she responds that they are a 4 and a 9. Jack tells her that those are the teleport base codes, which is all Jack needs to reactivate his vortex manipulator's teleportation ability. Jack grabs a large gun and promises Gwen and Ianto that he will come back, then vanishes.

Sarah heads off in her car to find the Doctor after Mr Smith promises to protect Luke. Rose contacts the parallel Torchwood and has them lock her onto the TARDIS before being teleported away.

The TARDIS lands in a trashed and deserted street. The Doctor asks Donna what Rose said in the parallel Earth and Donna replies with a smile, "Why don't you ask her yourself?" The Doctor turns around and sees Rose standing down the street. They run towards each other, absolutely delighted. As they get closer, a Dalek appears from behind a van and shoots at the Doctor, sending him to the ground. Captain Jack teleports into the street and blasts the Dalek to bits with his defabricator gun. A distraught Rose kneels over the Doctor as he lies on the ground in agony; Jack and Donna prepare to move him into the TARDIS.

Meanwhile, in Torchwood, Gwen and Ianto pick up machine guns and get ready for battle despite knowing full well that the guns are useless; Gwen is prepared to die in the line of duty like the recently deceased Owen and Tosh. A Dalek enters Torchwood and Gwen and Ianto open fire.

Back in the TARDIS, the Doctor is in terrible pain. Donna asks if there's anything they can do to help him but Jack tells her to stay away. The Doctor lifts up his hand, which has begun to glow.

Sarah is still in her car, driving down a street until she nearly hits two Daleks on the road. Despite her frantic attempts to apologise, the Daleks prepare to exterminate her: "Daleks do not accept apologies!"

On board the TARDIS, Jack wishes the Doctor good luck with his regeneration and makes the others back away. Donna asks about what is happening. Rose explains that when the Doctor is dying he can heal himself, but changes in the process. Rose doesn't want the Doctor to change as she has come a long way to find him, but the process has already started and can't be stopped. The Doctor gets to his feet. Glowing brighter and brighter by the second, he stretches his arms out as his body explodes into golden energy and begins to regenerate...

Cast

 * The Doctor - David Tennant
 * Donna Noble - Catherine Tate
 * Rose Tyler - Billie Piper
 * Martha Jones - Freema Agyeman
 * Captain Jack Harkness - John Barrowman
 * Sarah Jane Smith - Elisabeth Sladen
 * Harriet Jones - Penelope Wilton
 * Ianto Jones - Gareth David-Lloyd
 * Gwen Cooper - Eve Myles
 * Luke Smith - Tommy Knight
 * Wilfred Mott - Bernard Cribbins
 * Sylvia Noble - Jacqueline King
 * Francine Jones - Adjoa Andoh
 * Davros - Julian Bleach
 * General Sanchez - Michael Brandon
 * Suzanne - Andrea Harris
 * Trinity Wells - Lachele Carl
 * Himself - Richard Dawkins
 * Himself - Paul O'Grady
 * Drunk man - Marcus Cunningham
 * Newsreader - Jason Mohammad
 * Judoon - Paul Kasey
 * Shadow Architect - Kelly Hunter
 * Albino Servant - Amy Beth Hayes
 * Scared Man - Gary Milner
 * Dalek Operators - Barney Edwards, Nick Pegg, David Hankinson, Anthony Spargo
 * Dalek Voice - Nicholas Briggs
 * Voice of Mr Smith - Alexander Armstrong

Uncredited cast

 * Milkman - Andrew Bullivant
 * Jalandra - Mike Freeman
 * Judoon - Ruari Mears, Adam Sweet, Richard Tunesi, Jon Davey, Andy Jones
 * Judoon voice - Nicholas Briggs
 * Albino Servants - Hayley Jones, Rachael
 * Scared Man's Son (Simon) - Ethan Smith
 * Scared Man's Wife (Laura) - Jennifer Faubel

Worldbuilding

 * There is an advertisement for the Camden Fun Fair.

Earth businesses

 * Rose examines the Daleks' arrival on Earth via a laptop in the shop Megabyte City.

Daleks

 * Wilf uses a paintball gun as a weapon against the Daleks by shooting paintballs at their eye stalks, hoping to blind them; it proves to be completely ineffective.
 * The Vault Daleks lack the normal "plunger" attachment and now have a claw-like arm.
 * Similar to a Special Weapons Dalek, the Daleks' weapons can be increased in power enough to destroy a house, but this only works if three Daleks work together.
 * The Daleks of the New Dalek Empire were grown from the cells of Davros's body.

The Doctor

 * The Doctor says he likes Saturdays.
 * The Doctor is about to regenerate.

Planets

 * Only a few of the missing planets are mentioned by name: Callufrax Minor, Woman Wept, Clom, Pyrovillia, Adipose 3, the Lost Moon of Poosh, Jahoo, Shallacatop, and Earth.

Technology

 * Donna calls the subwave network an "outerspace Facebook".
 * A dimension cannon is used to travel between different parallel universes.

Story notes

 * This episode is the seven hundred and fiftieth broadcast episode of Doctor Who.
 * This episode was the last of Series 4 to have its title revealed.
 * This is the fourth time that the Daleks have returned with a leader in a finale. In The Evil of the Daleks, they returned led by their emperor; in the 2005 finale The Parting of the Ways, the Daleks were led by the Dalek Emperor; and in the 2006 finale Doomsday, Dalek Sec led the Cult of Skaro. The two-part Dalek story in 2007 was shown as the fourth and fifth episodes of the series. (TV: Daleks in Manhattan/Evolution of the Daleks)
 * This is the first episode to feature a Dalek designated as the Supreme Dalek since Remembrance of the Daleks.
 * There was originally a scene where a Dalek Saucer landed at Westminster (destroying Big Ben in transit) and one in which the Daleks exterminated the Prime Minister, Aubrey Fairchild, before the Dalek invasion force emerged from the saucer. An unseen character in The Next Doctor was named Aubrey Fairchild.
 * The "To Be Continued" before the end credits is different from the others previously used. There is also no sneak peek of the next episode, probably to avoid revealing what has happened to the Doctor after his regeneration. It is only the second episode (after Rise of the Cybermen) that has used this method of continuation. It would later be employed in The Pandorica Opens, The Almost People, Dark Water and The Zygon Invasion.
 * When Harriet Jones contacts Captain Jack, Martha Jones, and Sarah Jane Smith, the contact tone is the same tone used by to control the populace under the Archangel network.
 * For the first time, the opening credits incorporate not two or three names, but six, adding Freema Agyeman, John Barrowman and Elisabeth Sladen to the Tennant, Tate and Piper credits of the previous week. The typeface used for these credits is slightly different than that usually used. In addition, several "overflow" cast credits are featured over the first scene after the opening sequence, a first for the series (Penelope Wilton, Adjoa Andoh, Eve Myles and Gareth David-Lloyd). Although the appearances of Harriet Jones and Francine Jones are clearly intended to be surprises, the surprise is weakened for anyone who recognised the names of Wilton and Andoh in these opening credits. Despite their major roles in this episode, neither Bernard Cribbins nor Jacqueline King received similar credits.
 * Scientist and author Richard Dawkins has a cameo as himself. Dawkins was married to Lalla Ward, the actress who portrayed Romana II at the time. The two were introduced by Douglas Adams, who met Ward in his capacity as the show's script editor during the time Ward's ex-husband, Tom Baker, played the Fourth Doctor.
 * As chronicled in The Writer's Tale, the first draft of the script simply called for an elderly professor. It was Benjamin Cook, as part of his extended correspondence with Russell T Davies, who suggested Dawkins fill the role (to which Davies enthusiastically agreed).
 * The claws of the Daleks in Crucible are very similar to ones in the Dr. Who and the Daleks movie, but with eight fingers instead of two.
 * The clicking sound when the Time Beetle from Turn Left was mentioned occurred when Donna was offered water at the Shadow Proclamation, accompanied by the same words used when the Time Beetle was "seen" by somebody else: "There's something on your back!"
 * The original Sci-Fi channel broadcast in the United States cut some scenes to fit the different commercial times.
 * The differences between the child-friendly Sarah Jane Adventures and the very adult-orientated Torchwood are reflected in the onscreen conference. Sarah mentions that she tries to steer away from Torchwood because they have "too many guns", nodding to Luke as she does so. Despite this, Jack cannot resist flirting with her and she seems to appreciate his compliment.
 * The concept of the bees leaving the earth and heading to another planet as it seems the end is near strongly reflects the dolphins from The Hitchhiker's Guide to the Galaxy, who also left the planet right before its impending doom. Though most likely a coincidence, it should be noted that Douglas Adams, who wrote Hitchhiker's Guide, was a writer and script editor for Doctor Who.
 * Another reference to The Hitchhiker's Guide to the Galaxy occurs when a Dalek near the start of the episode shouts, "Resistance is useless." This line was often used by Vogons (an alien in THGTTG) when they captured Arthur Dent and Ford Prefect.
 * The CGI shot of the Doctor's TARDIS flying toward the Shadow Proclamation was previously used in The Parting of the Ways, where the Ninth Doctor flew the TARDIS into battle against a Dalek fleet, which bombarded it with torpedoes. Coincidentally, this episode is also centred around a major Dalek conflict.




 * The scene in the Shadow Proclamation was originally planned to show many more aliens old and new including:
 * Raxacoricofallapatorians with a child. This child was originally conceived as Margaret following her regression to an egg (TV: Boom Town)
 * Baby Adipose and very big adult one (imagined by Russell T Davies as being about fifteen feet tall)
 * Scholars of the University of Rago Rago 56 Rago or members of the same species
 * Krillitane
 * Vespiform
 * Hath
 * Gelth-like species
 * Cybermen
 * Sycorax
 * Alonso Frame working for the Shadow Proclamation as a Shadow Soldier
 * Isolus
 * Graske
 * Kroton
 * Hoix
 * Chelonian-like species
 * Two-headed race (Aplans?)
 * The Bane


 * While this scene was not transmitted in this episode, it could have been scaled down to become the space-bar scene in the final scenes of the second part of The End of Time. According to Russell T Davies, this version of the scene was never put into development due to the heavy toll it would've taken on the episode's budget.


 * When Sarah summons Mr Smith, she complains about the musical fanfare that accompanies the computer's activation; this is the culmination of a recurring gag in The Sarah Jane Adventures in which the same fanfare usually blares whenever Mr Smith is activated. This is the first time, however, that it is confirmed the characters actually hear this music.
 * An ongoing question relating to why the Doctor can't or won't go back to the era of the Time War to make things turn out differently is addressed by the Doctor indicating that the war is time-locked; Dalek Caan, having circumvented this barrier, paid for the experience with his sanity.
 * This story was chosen by BBC America to represent the David Tennant era during their 50th-anniversary programming. Edited into an omnibus format with Journey's End, it was aired by BBCA on 27 October 2013, after the debut of their homegrown special called The Doctors Revisited - The Tenth Doctor.
 * When Russell T Davies planned out season four, he envisioned the original companion Penny Carter in this episode, with Donna merely making a cameo, although there were concerns that Catherine Tate's schedule would prevent this.
 * Euros Lyn was originally assigned to direct, but he was moved to Silence in the Library/Forest of the Dead instead.
 * Some thought was given to including Maria Jackson and Clyde Langer.
 * Russell T Davies had been impressed with Russell Tovey's performance as Alonso Frame in Voyage of the Damned and wanted to include him in the story. He would appear when the Doctor and Donna travelled to the Shadow Proclamation, and assist them in dealing with his superiors there. He would then journey with them in the TARDIS to the Dalek Crucible, only to be exterminated, allowing Davies to sacrifice somebody recognisable without having to kill off one of the show's better-established characters. This had been a concern for Davies during his development of the narrative, because he felt that the death of one of the Doctor's allies was necessary to demonstrate the scale of the adventure. This was scrapped when Tovey became unavailable.
 * Harriet Jones was brought back because both Julie Gardner and Phil Collinson felt that she was due a redemption.
 * It was not initially certain that Penelope Wilton would be free to reprise her role of Harriet Jones, and so Russell T Davies was also prepared to replace her with Mr Copper, Elton Pope, or Joan Redfern's great-great granddaughter. At one point, he considered having either Polly Wright or Tegan Jovanka fill her role
 * Originally, only six planets were required for the Daleks' scheme.
 * Russell T Davies' writing was affected by the development of a head cold and overrunning script constraints; he was annoyed that he had written "dialogue [he had] been dying to write" with a "faint heart" because he would have to cut it. Because he was behind schedule, he was forced to cancel plans to attend Billie Piper's wedding and almost cancelled plans to celebrate the New Year with his boyfriend. These problems affected his first draft of the Doctor's conversation with his companions and encounter with Davros; he dismissed it as "lame shit" which would waste licence-payers' money, and replaced it with a different version hours later. He eventually finished the script at 1 am on New Year's Eve.
 * David Tennant, Catherine Tate and Graeme Harper all made the creative decision to have the Doctor ignore any mention of the Daleks in his conversation with his companions, because they thought the Doctor's joviality in the scene would be otherwise inappropriate.
 * The scene in which Wilfred attempts to blind a Dalek using a paintball gun was suggested by Bernard Cribbins himself. He proposed it as a reference to Daleks' Invasion Earth 2150 A.D., which he appeared in, and thought it would provide comic relief in between heavy exposition. He also ad-libbed Wilf asking Rose to swap weapons after she blows up the Dalek.
 * General Sanchez was originally named Slade.
 * The Dalek's evaporating the paintball and replying "My vision is not impaired!" was added after Benjamin Cook reminded Russell T Davies it was "obligatory" to invert the recurring phrase spoken when a Dalek was blinded ("Vision impaired!"), and remove a weakness the Daleks had exhibited since their first appearance.
 * There was originally a lengthy flashback chronicling Davros' youth on Skaro, his experiments on Kaled soldiers, and the explosion which disfigured him.
 * The task of redesigning Davros fell to Neill Gorton of Millennium FX. Two Davros masks had been used in the classic series, and it was agreed that the new version should hew towards the original from Genesis of the Daleks, rather than the more distorted mask introduced in Resurrection of the Daleks. Davros' life support unit was newly-constructed, and was intended to have a sturdier appearance than the old prop. The only addition made was the metallic hand, as his real hand had been shot off in Revelation of the Daleks.
 * Russell T Davies wanted the Supreme Dalek to have a red livery as a nod to one of the main Daleks seen in Dr. Who and the Daleks and Daleks' Invasion Earth 2150 A.D. A variety of possible designs were considered, including some with an oversized dome reminiscent of a samurai helmet, and others which boasted an enormous gun arm, inspired by the Special Weapons Dalek. The additional struts on the finished version were suggested by the antennas on Sputnik 1.
 * One of the Daleks built for Bad Wolf/The Parting of the Ways was now being used exclusively for exhibitions, so a replacement was needed. The original casing from Dalek was also restored to its bronze colour scheme, having been painted black to serve as Dalek Sec.
 * The scenes in the TARDIS were the first material to be filmed.
 * This two-parter comprised of Block Nine of season four.
 * Penelope Wilton filmed her scenes in one day. She agreed to return unconditionally because she "would do anything for ... Davies" and she wished to act in Phil Collinson's last filming block as producer
 * Paul O'Grady's cameo was filmed on the set of The New Paul O'Grady Show at The London Television Centre in Waterloo.
 * Terry Molloy was asked to reprise his role as Davros, but declined, as he was not fond of Russell T Davies' prior work.
 * The staircase which Donna is sitting on at the Shadow Proclamation is the same staircase on which Owen Harper fights death in Dead Man Walking.
 * There was a plan in one draft to have Sparrow & Nightingale to be crushed by a Dalek ship, but this scene wasn't filmed.
 * Russell T Davies considered destroying New York, but decided against it.
 * Russell T Davies had included a cameo role for Annette Badland as Margaret, who would now be in the care of the Jingatheen, but would react badly to the presence of the Doctor. Badland had already recorded accompanying dialogue but, unfortunately, it would go unused.
 * Rose almost didn't appear due to Billie Piper's honeymoon clashing with the original recording dates.
 * Russell T Davies compared the crossover's conception to a typical child's imagination of a crossover between the Doctor Who and Star Wars universe.
 * Instead of hearing the Daleks' repeated cry of "Exterminate", Captain Jack and Sarah Jane originally reacted to the sight of Dalek saucers.
 * Russell T Davies and Phil Collinson lamented killing off Harriet Jones. Collinson "[couldn't] bear the thought she's dead" and argued that she escaped death; and Davies generally stated in Doctor Who Magazine issue 397 that "when [significant characters a writer creates] have to die, it's a genuinely emotional time"
 * Russell T Davies wrote the climax as a pastiche of romance fiction and compared the reunion between Rose and the Doctor to "the biggest romance [the viewer] has ever seen" and joked that seminal films such as Gone with the Wind should have ended with a Dalek shooting the male lead, and intensified the scene's emotional impact through Billie Piper's cameos throughout the fourth series.
 * David Tennant described the Doctor's wounding as a "moment of high emotion" and lamented that "[the Doctor] can't have a happy moment, especially with a cliffhanger needing to be written".
 * The episode ended during the regeneration because Russell T Davies wanted to create the "biggest, most exciting cliffhanger in Doctor Who", and to differentiate the scene from previous regenerations, which were always completed at the end of serials. He considered its resolution—the regeneration process being halted by the Doctor, who siphoned the excess energy into his severed hand after his injuries were healed—legitimate because the hand was an important plot device in Journey's End 's climax.
 * Gary Milner was cast as the extra "Scared Man" after misreading the callsheet as "Sacred Man" and creating a "priest-like" portrayal of the character.
 * Andrew Bullivant's role as the milkman in the cold open led to him being cast as a policeman in The Tempation of Sarah Jane Smith.
 * Russell T Davies postponed Davros' return as he thought that "Davros would dominate the Daleks... like plain robots, instead of the scheming geniuses that they are", and used the previous series to establish the Daleks' individual intelligence.
 * Russell T Davies cast Julian Bleach as Davros after his performances in his Olivier Award-winning play Shockheaded Peter and as the Ghostmaker in From Out of the Rain.
 * To keep the return of Davros secret, the character was referred to as "The Enemy" or "Dave [Ross]" among the crew and was kept anonymous on the shooting scripts as much as possible; however, the Radio Times called the secret "one of the worst-kept ... in television history".
 * David Tennant liked Davros' "Hitlerian megalomaniac" attitude and the nostalgic feeling he created. He described himself as being "absolutely captivated by [the] extraordinary creature".
 * To prepare for his role, Julian Bleach reviewed Genesis of the Daleks, one of his favourite serials, to remind himself of Davros' voice.
 * Julian Bleach described his interpretation of Davros as that of "[a] twisted megalomaniac, [a] mad scientist, [and a] misguided genius" at the same time and described the character as a whole as "a cross between Hitler and Stephen Hawking" whose "nihilistic desires" made the character "extraordinary". Bleach would later use Hitler's oratorical skills and his "dogmatic speeches" as a reference point.
 * The production team made two minor changes to Davros' design: they removed his microphone and completely redesigned the headpiece. The team felt that the microphone was redundant because Davros did not "speak in a whisper and need something to make him more audible", and originally intended to leave Julian Bleach's voice unaltered in post-production: the decision to treat the voice was not made until late May 2008; and Neill Gorton thought the original headpiece "always seemed particularly weak" for "such a powerful character". After he was informed that the production designer for Genesis of the Daleks wanted the headpiece to resemble a medical brace, Gorton redesigned it to appear to be "screwed directly into [Davros'] head".
 * Concept artist Peter McKinstry aimed to make Davros "bigger and scarier" by updating the "flimsy" design of the classic series.
 * Louise Page and Neill Gorton contemporaneously collaborated on Davros' upper body. Page designed the leather tunic—which Gorton thought was "a beautiful piece of costume...which echoes the classic design"—and Gorton designed the ribcage. Russell T Davies explained the use of the leather tunic and the exposed ribcage: "Seriously, Davros is meant to be horrific, and we've had so many withered geniuses in sci-fi lately–like Emperor Palpatine in Star Wars–that I needed something to make everyone sit up and realise that this man is the King of Horror: the original and the best! And he's been through so many physical changes over the years, I wanted to add one of my own. I asked Louise to give him the new jacket buckles, because I wanted it to look like a straitjacket. It just seemed to fit, cos he's so insane!"
 * Russell T Davies compared the crossover's conception to a typical child's imagination of a crossover between the Doctor Who and Star Wars universes: "When you see the story, it'll make so much sense that all these characters are involved. It's simply doing what kids do in their imaginations: they're experts at crossovers and would think of nothing of having their Dalek toys battling Star Wars droids. Why not have all the factions of the Doctor Who universe going into battle together?"
 * The animatronic of the Dalek mutant had to be recreated for the episode, because the previous prop that was used in Dalek and The Parting of the Ways was irreversibly damaged by water when the latter was filmed.
 * This was the first appearance of the Daleks since Evolution of the Daleks; consequently, the prop controllers experienced difficulty re-adapting to their roles.
 * Russell T Davies' inclusion of the Daleks as part of the crossover was intended to create a "charged atmosphere" for the protagonists: Jack was killed by the Daleks; Rose and Martha were present at two of their apparent extinctions; and Sarah was present at their creation.
 * Nicholas Briggs adopted a different voice for each Dalek model: he adopted a grandiose voice for the Supreme Dalek to fit his perception of the character as egotistical; and he adopted a sing-song voice for Caan to reflect the character's insanity as a result of entering the Time War.
 * Nicholas Briggs justified his interpretation of Caan by explaining that "[Caan] can't tell when he's happy or sad, his emphasis is very strange and he finds things funny when things aren't funny", creating a soothsayer personality with an "almost pure" mind.
 * Nicholas Briggs told Doctor Who Magazine: "My theory on Caan is that being sucked through the Time War and blown out the other end has kind of reverse-wired–or random-wired–his brain, so all his neurons are firing in constantly changing, random, insane ways. That's why he doesn't really know what's funny or serious. He just knows the truth, and it blurts out in this odd, cryptic way. I think he's frozen in a moment of excrutiating [sic] ecstasy. When any emotion surges up inside him, it makes him laugh, whether its appropriate or not".
 * Nicholas Briggs' portrayal of Caan was well-received by the production team: Graeme Harper "loved Caan's giggling" and requested "more ... on every take"; and Russell T Davies described Caan as "the creepiest Dalek yet".
 * The Dalek eyestalk exhibits a minuscule twitch in scenes, a characteristic added by Graeme Harper to make them appear cautious and "on-edge".
 * The episode features the first external location shots of the Daleks and the greatest proportion of filming undertaken at night since the show's revival: apart from the pre-credits sequence set in suburban London, all of the scenes set on Earth were filmed at night.
 * David Tennant and Catherine Tate filmed the trailer for the fourth series because they were not required on location.
 * The Doctor and Rose's reunion was filmed in Penarth town centre, in front of two hundred people; consequently, the scene was leaked onto the Internet and reported in the next day's edition of The Sun.
 * Graeme Harper insisted that the Doctor and Rosee's reunion appear "mystical" because the characters' reunion was "the most magical moment" in the entire episode and Ernie Vincze, the Director of Photography, compared the scene's feeling to Blade Runner.
 * The production team was prepared to postpone filming due to a traffic accident on the first day of filming.
 * Filming Hariet Jones' death scene was stalled because of difficulty transporting the Dalek props into the cottage: specifically, the raised patio doors made it difficult to balance and maneuver the props.
 * The Mill created two notable effects: the invasion of New York City, using reconnaissance photos and establishing shots from the filming of Daleks in Manhattan to create a 2.5D shot of the city; and the planetary array at the Medusa Cascade, using a fully three-dimensional model.
 * The number of effects in the first draft was almost three times larger than broadcast; consequently, several scenes—most notably, all but one shot of the attack on the Valiant—were cut from the episode.
 * The last exterior scene filmed was recorded in the regular The Sarah Jane Adventures filming location of Clinton Road in Penarth, and consisted of external shots of Sarah's house and two Daleks accosting Sarah en route to meeting the Doctor.
 * Richard Dawkins and Paul O'Grady's cameos were the last scenes to be filmed.

Ratings

 * 8.78 million (UK final)

Myths and rumours

 * The presence of Davros in this episode had been rumoured for a long time before broadcast. An associated rumour suggested that the episode would reveal that Donna was actually Davros in disguise or Caan mutated himself into Davros. See this section in Journey's End for additional rumours related to Donna.
 * It was also rumoured on the fan boards that Patrick Stewart or Ben Kingsley might have been cast as Davros. The speculation surrounding Stewart followed media reports of his interest in appearing in Doctor Who after it was announced that he and Tennant would perform a season of Shakespeare together in 2008. Ultimately, Julian Bleach was revealed to be playing the character.
 * The cliffhanger regeneration ending sparked a week's worth of widespread speculation as to whether David Tennant was in fact about to hand the role over to another actor, despite reports that he was to at least appear in the upcoming Christmas special. The rumours, of course, were put to bed upon the cliffhanger's resolution.
 * It was also rumoured that there would be a massive fight between the Judoon and the Daleks that would decide the fate of planet Earth. This was proven false.
 * It has been rumoured, but never confirmed, that Russell T Davies was originally planning to bring back Clive Swift as Mr Copper from Voyage of the Damned, but changed his mind after Swift's interview for DWM 391 in which he refused to answer some questions and insulted the interviewer Benjamin Cook, the franchise, and the fandom in general before terminating the interview altogether.

Filming locations

 * Cardiff
 * Pontypridd
 * The Water Tower, Roald Dahl Plass (also filmed for Torchwood)
 * 21 Clinton Road, Penarth (13 Bannerman Road, Ealing (also filmed for The Sarah Jane Adventures))


 * High Street, Penarth (The Doctor and Donna arrive back on Earth)


 * Queen’s Road, Penarth (Rose materialises and runs to the Doctor)
 * Arcot Street, Perth (Jack materialises and destroys the Dalek)
 * Brook Street, Riverside, Cardiff (Daleks round up prisoners on the protesters’ house)
 * South Wales Traffic Management Centre, Coryton, Cardiff (UNIT HQ in New York)
 * Lower House, Michaelston-le-Pit, Cardiff (Harriet’s House)
 * Wales Museum Collections Centre, Heol Crochendy, Parc Nantgarw (Martha is taken to Project Indigo)
 * Cwrt-y-Vil Road, Penarth (Martha materialises at her mother’s house)

Production errors

 * In the scene just before Martha teleports with Project Indigo, her earpiece disappears, then reappears when she takes it off.
 * When Jack hears Martha use Project Indigo, in spite of him kicking his filing cabinet to drown it out, he can still clearly be heard screaming "Shit!"
 * When Harriet Jones transfers the Subway Network to Torchwood, the UI animation of the transmission has the map end up in Swansea, instead of Cardiff, where the Hub is.
 * When the Daleks discover the location of the subwave network has been moved to Torchwood, the Dalek who announces it to the Supreme Dalek only has its eyestalk light turned on just as he says Torchwood, which is the last word of the line.
 * The Bluray release of this story uses the wrong font to credit the additional cast immediately after the opening titles. Traditionally, the font used for the Russell T Davies era is "Futura Book", however the font used on the Russell T Davies era blu-rays is "Futura Medium", and this font is still used to credit the Producers and for the title card. An entirely different font - "Tahoma" - is used to credit Penelope Wilton, Adjoa Andoh, Eve Myles and Gareth David-Lloyd in this episode. The error is repeated in Journey's End.

Continuity

 * The Doctor and Donna visit the Shadow Proclamation, which was previously mentioned in the television stories and
 * Sarah Jane believed Davros to be dead, as she'd last seen him in TV: Genesis of the Daleks, where he appeared to be so.
 * Earth is taken to the Medusa Cascade. (TV: Last of the Time Lords, The Fires of Pompeii)
 * The Doctor refers to the lost moon of Poosh. (TV: Midnight) Donna likewise mentions Pyrovillia, (TV: The Fires of Pompeii) and the Adipose's breeding planet. (TV: Partners in Crime)
 * Donna mentions how the bees were disappearing. (TV: Partners in Crime)
 * The Valiant is swarmed and destroyed by a huge group of Daleks. (TV: The Sound of Drums, Last of the Time Lords, The Poison Sky)
 * UNIT have fought Daleks before. (TV: Day of the Daleks, et al.)
 * Sarah refers to the Doctor having deposed Harriet Jones. (TV: The Christmas Invasion)
 * The gun that Captain Jack used to kill the Dalek with appears to be the same gun he previously used against them. (TV: The Parting of the Ways)
 * The Doctor previously disabled the teleportation function of Captain Jack's vortex manipulator. (TV: Last of the Time Lords)
 * Gwen states to Ianto, after handing him a firearm during the Dalek invasion of Torchwood 3, that she intends to "go out fighting" like Owen Harper and Toshiko Sato. (TV: Exit Wounds)
 * The Doctor mentions that someone tried to move the Earth "a long time ago." The Daleks once tried to place a drive system into the centre of the Earth so that they could pilot the planet. (TV: The Dalek Invasion of Earth)
 * The Time Lords successfully relocated the Earth, causing it to become known as Ravolox. (TV: The Trial of a Time Lord) The Cybermen also successfully moved and piloted Earth's twin planet, Mondas. (TV: The Tenth Planet)
 * Sarah Jane Smith, Rose, Jackie, Mickey, Jack and Martha have all met Daleks before. (TV: Death to the Daleks, Genesis of The Daleks, Dalek, Bad Wolf, The Parting of the Ways, Doomsday, Daleks in Manhattan, Evolution of the Daleks)
 * Donna is told that she had something on her back. (TV: The Fires of Pompeii, Turn Left)
 * The Doctor again encounters the Judoon. (TV: Smith and Jones, PROSE: Revenge of the Judoon).
 * The Daleks proclaim that "the Daleks are the masters of Earth!". They also issued the command for "the males, the females and the descendants" to come into the street and surrender to them. (TV: The Dalek Invasion of Earth)
 * Jack refers to Sarah's encounters with the Slitheen. (TV: Revenge of the Slitheen, The Lost Boy)
 * The Emperor of the Daleks referred to Rose as "the Abomination", (TV: The Parting of the Ways) as the Dalek Supreme does to Dalek Caan. This is also the name given to the Special Weapons Dalek. (PROSE: Remembrance of the Daleks)
 * The Doctor was last seen meeting Davros during his eighth incarnation. (AUDIO: Terror Firma) They refer to having had at least one more encounter, during the Time War. Davros acknowledges that the Doctor has changed again since their last meeting.
 * The Third Doctor was also shot by a Dalek. On that occasion, his legs were temporarily paralysed. (TV: Planet of the Daleks)
 * Upon answering the phone to Martha, Jack says, "Martha Jones, voice of a Nightingale". (TV: Reset)
 * Davros now has a mechanical, skeletal hand, replacing the organic one shot by Boston. (TV: Revelation of the Daleks, AUDIO: The Davros Mission)
 * In previous encounters (TV: The Daleks, Planet of the Daleks, Resurrection of the Daleks, Revelation of the Daleks, The Parting of the Ways) in which a Dalek eye would be shot, or covered, the Dalek would cry hysterically, "My vision is impaired! My vision is impaired!" When Wilfred attempts to exploit this weakness here and shoots a Dalek in the eye with his paint gun, it says, "My vision is not impaired".
 * Harriet Jones again introduces herself by flashing her identity card, earning her the response of "Yes, I/we know who you are", even from the Daleks. (TV: The Christmas Invasion)
 * Luke's comment about spatial transference echoes a similar statement made by Grace Holloway when she revealed unexpected knowledge of physical theory. (TV: Doctor Who)
 * The Doctor has previously had a group of soldiers aim their guns at him. (TV: Aliens of London, World War Three, Dalek, Army of Ghosts) This time, rather than humans, they are Judoon.
 * General Sanchez is heard saying, "Ladies and gentlemen, we are at war." The same phrase was spoken by Jack Harkness when facing the Daleks on the Game Station. (TV: The Parting of the Ways)
 * Woman Wept was mentioned by Rose when talking to Mickey of the planets she had visited. It had experienced an unknown sudden freezing of its oceans, which at the time was unexplained. (TV: Boom Town)
 * The missing planet Callufrax Minor may be a reference to Calufrax, the miniaturised planet and Key to Time. (TV: The Pirate Planet)
 * When the sub-wave network patches through to Rose at Donna Noble's home, the ringtone matches the rhythm of the drums that the Master spoke of. (TV: Utopia, The Sound of Drums, Last of the Time Lords)
 * The Doctor can speak Judoonese. (AUDIO: Judoon in Chains)
 * The Tenth Doctor and Donna previously met Judoon on Vallarasee. (AUDIO: One Mile Down)
 * A few years prior, Major A Highway was responsible for reorganising UNIT in the United States into a "single site operation", (PROSE: UNIT's New York Operation Expansion) having been previously split into multiple divisions such as UNIT ONE and UNIT THREE. (PROSE: The Dying Days)

Home video releases

 * This story was released in the Series 4 DVD box set in November 2008 along with the rest of the series.
 * It was released as Series 4 Volume 4 in a vanilla edition with Turn Left and Journey's End.