Doomsday (TV story)

Doomsday was the was the thirteenth and final episode of series 2 of Doctor Who.

It was the final regular appearance of Billie Piper as Rose Tyler and introduced Catherine Tate as the future companion Donna Noble in its closing moments.

Narratively, the destruction of Torchwood London seeded the way for the spinoff Torchwood, where Torchwood Three eventually became all that remained of the Institute. The Cult of Skaro escapes at the climax of this episode, starting a string of Dalek stories which eventually concluded with the reestablishment of the Daleks as a race beyond survivors of the Time War in Victory of the Daleks, four years later.

Tardisode 13 occurs during the events of this episode, when the battle reaches a climax. It is the last of the Tardisode series, ending with the series 2 finale.

Synopsis
A secret order of Daleks emerge and the Cybermen from Pete's World make their way to Torchwood Tower. As the two deadly forces fight over Earth, the Tenth Doctor realises that in order to stop the threat, sacrifices will be made.

Plot
Dr Singh, Mickey Smith and Rose Tyler are trapped in a sealed room within Torchwood Tower as the four Daleks who have emerged from the void ship approach them, with a vaguely Dalek-shaped artefact following. As they cry out their intent to exterminate, Rose bellows their name which stops them in their tracks. She approaches the black Dalek and offers to tell them how she knows about the Daleks and the Time War if they keep them alive, with Mickey and Dr Singh playing along. The black Dalek decides that they are necessary and asks about the status of the artefact — which it calls the Genesis Ark. It orders the awakening to begin (with one of them proceeding to monitor the Ark) and declares that the Ark must be protected above all else. The black Dalek giving commands exudes leadership.

The Cybermen hold Jackie Tyler, Yvonne Hartman, and the Tenth Doctor hostage. The Cyber-Leader demands to speak to the world leader. Yvonne says they don't have one, to which the Cyber-Leader replies that they have now. The Cyber-Leader interrupts all television to make a message in which it promises to convert all humans into Cybermen. There appear to be Cybermen in every home on Earth, and Cybermen are said to be on every landmass. However, despite the call for surrender, the British Army mobilises and soon fighting and fire have spread across the whole of London, with both sides taking losses. The Cyber-Leader is confused that humanity hasn't surrendered, to which the Doctor angrily snarls that mankind is not taking instructions; the Cybermen are "on every street, you're in their homes, you've got their children! Of course, they're gonna fight!"

The black Dalek demands that the trio identify which is least important which Rose refuses to answer, but Dr Singh volunteers, knowing he is of no importance compared to the two time travellers. They ask him to kneel down, saying that they need to know everything they can about current Earth history. Singh begins to respond but the Daleks say that speech is not required. Three of the Daleks place their plungers around his skull and stretch his brain. A few minutes later, his mutilated corpse drops to the floor. Rose yells at the Daleks that they didn't need to kill him, but they state they didn't need him alive either.

The Cybermen then notice other lifeforms in the building and send Cyber units Ten-Six-Five and Ten-Six-Six to the Void Room to investigate. At the same time, the Daleks notice lifeform readings and the black one orders one of its compatriots, addressing it as Dalek Thay, to investigate. The Cybermen and the Dalek meet in the corridor outside the Void Room. The Doctor, Jackie, Rose and Mickey can see them both through video transmissions and the Doctor is visibly horrified to see the Dalek.

The Cybermen ask that the Daleks identify themselves and the Daleks demand the same. Neither complies and there is a stand-off, which Mickey describes as "Stephen Hawking meets the Speaking Clock". The Daleks accidentally slip up when Dalek Thay says that "Daleks do not take orders", but recognise the Cybermen, comparing them to their own universe's Cybermen. The Cybermen and the Daleks exchange insults until the Cybermen offer to form an alliance with the Daleks to overtake Earth, and eventually upgrade the universe, together. The Dalek refuses and the Cybermen respond with laser fire; the Dalek shrugs off the shots and almost dismissively exterminates them both in seconds.

The Cyber-Leader warns the Daleks that they have declared war on the Cybermen, to which the black Dalek replies, "This is not war, this is pest control!" It then mockingly states that Cybermen are only superior in one respect; they are better at dying. One of the other Daleks then spots the Doctor on the screen, and the Daleks register him as an enemy but fail to recognise who he is exactly. The black Dalek recognises that Rose's heartbeat has increased, causing Mickey to say, "Yeah, tell me about it!" The Daleks demand to know who the man on the screen is. Rose tells them that it is the Doctor and the Daleks actually scoot back a few inches in fear. Rose is amused that five million Cybermen are easy, but one Doctor has got the Daleks scared.

After a brief conversation with the Doctor about Rose's safety, Jackie is dragged away to be upgraded along with Yvonne Hartman. The Doctor promises he will save Jackie and get her out alive before she is taken away. The Cyber Leader comments that the Time Lord is proof of how emotions weaken humans. The Doctor agrees but then says that he quite likes hope, and in that instant, a team with guns suddenly appear and destroy all Cybermen in the Breach Room. The leader of the team reveals himself to be Jake Simmonds.

In the area the Cybermen were hiding in, sparks and screams are coming from the Torchwood personnel as they are converted into Cybermen. Yvonne explains to Jackie that their brains are going to be placed in the Cybermen shells, angering Jackie. Jackie tells Yvonne that what is happening now is Torchwood's fault and she has brought death and destruction to the Earth. Yvonne is taken away, as she tries to remind herself that what she did was for 'Queen and country'. Shortly after, the Cybermen receive an update that the original Cyber-Leader has been killed and begin to download his files into another Cyberman unit, enabling Jackie to escape down the stairwell.

Meanwhile, the Doctor tells Jake that they cannot just hop from one universe to another. Jake shows the Doctor the disc-shaped devices they developed with their world's version of Torchwood, and before the Doctor can stop him, Jake transports the two of them. Jake explains that they found out what the parallel Torchwood was doing and the People's Republic took control. As the Doctor asks Jake to take him back, Pete Tyler steps out of the shadows, telling the Doctor that this is their world and for once, he is going to listen.

Dalek Thay returns to the Sphere room, suggesting that they should concentrate on the Genesis Ark before attempting to battle the Cybermen. The black Dalek orders the other Daleks to begin the awakening and all four attach the ends of their manipulator arms to four spheres which are positioned on the Ark's four sides.

Pete explains that they tried sealing up the Cybermen in the factories, but other people argued that the Cybermen were still people and needed help. As the debate went on, the Cybermen infiltrated the parallel Torchwood, found the Doctor's universe and vanished; they realised their home world was too prepared to fight them off, but the Doctor's universe had less advanced weapons that could destroy them. The sheer mass of five million Cybermen is why it took them three years to cross while individuals could pop across in a second.

Mickey reveals to Rose that he has one of the dimension-jumping devices, but it can only transport him, saying the Daleks won't need him or Rose. Rose proceeds to wonder aloud why the Daleks would build something they couldn't open (having realised that the Daleks need a time-traveller's touch to open the Ark). The black Dalek, having overheard the conversation, declares that the Daleks did not build the Ark, stating it is of Time Lord design, claiming the Ark is the last remnant of Time Lord society (other than the Doctor and the TARDIS). When Rose asks what is inside, the Dalek only replies enigmatically, "The future."

Pete shows off his world, where Great Britain is apparently enjoying a Golden Age, and where Harriet Jones is President. However, ambient temperatures are rising and the ice caps are melting. Pete correctly surmises that it has to do with the breach; the Doctor confirms that every time someone crosses over damage is done, and if it keeps up both worlds will fall into the Void. Pete believes the Doctor can close the breach, but when the Doctor says that doing so will leave the Cybermen and Daleks on his world, Pete replies that he is only interested in protecting his Earth. The Doctor points out there is a parallel Jackie who is still alive but Pete says that there are more important things at stake and asks the Doctor to help them. Revitalised by Pete's faith in him, the Doctor agrees to help.

The Doctor, Pete and Jake cross back. The Doctor calls up Jackie on her mobile phone, telling her to keep a low profile in the stairwell. The Doctor takes Jake's rifle and modifies it so it can affect polycarbide, the skin of a Dalek. He then surrenders a "very good idea" unto the Cybermen (using a piece of white A4 paper on a stick in place of a little white flag) and the two sides agree to work together.

The black Dalek demands that Rose activate the Ark, threatening Mickey's life. Rose steps forward to do so, but then decides to bring up how she met the Dalek Emperor. The black Dalek is astonished (as much as it can convey) to learn that the Emperor survived, but Rose gleefully recounts how she used the time vortex to turn him to dust. "The God of all Daleks, and I destroyed him!", she exclaims with a delighted laugh. The furious Dalek is about to exterminate her for this when the Doctor appears in the doorway, which changes its priorities somewhat.

The black Dalek asks how the Doctor survived the Time War. The Doctor says that he did that by fighting on the front lines, whereas these Daleks fled. Rose tells the Doctor that these Daleks have names, a fact which the Daleks confirm by declaring each of their names respectively: Dalek Thay, Dalek Sec, Dalek Jast and Dalek Caan. The Doctor realises that these four Daleks are members of the Cult of Skaro, a secret order above even the Emperor. The Cult's purpose was to think as the enemy thinks, to find new ways of killing, including daring to take on individual identities. When Mickey asks the Doctor about the Genesis Ark, the Doctor replies that he doesn't know what it does; both sides had secrets.

Dalek Sec gloats that Time Lord science will ensure the supremacy of the Daleks, and orders the Doctor to open the Ark. The Doctor laughs off the suggestion and produces his sonic screwdriver. He explains that, while it cannot kill, wound, or maim, it is very good for opening doors, a fact he demonstrates by using it to explosively open all the doors leading into the sphere chamber. The Cybermen enter and open fire on the Daleks using the modified energy rifles, temporarily disrupting Dalek Thay's shields and weapons and giving the Doctor and humans time to escape. However, the Daleks quickly adapt and regain control of their weapons and return fire without mercy, concentrating their attacks on the Cybermen. As the Doctor and the humans rush out of the chamber, Mickey is knocked into the Ark by a damaged Cyberman and his hand presses against its surface. After the Daleks easily exterminate the Cybermen, the Ark is primed, steam gushing from the bottom vents, but Dalek Sec says that it needs a space of thirty square miles to activate. The Daleks begin to escort it out of the chamber.

The Doctor and the humans retreat towards the stairwell. As they are running, Mickey apologises for his slip-up, but the Doctor tells him that he did them a favour because the Daleks would have otherwise tried to open the Ark by force and to do so they would have blown up the Sun.

Jackie is found by two more Cybermen who lurch forward to capture her for upgrading but are shot from behind by Pete, with the Doctor, Rose and Mickey following him. Jackie and Pete see each other for the first time and have an awkward exchange as their parallel counterparts are dead. Although Pete tries to rationalise that Jackie is not really his wife, the two end up running into each other's arms and embracing.

The Daleks and the Ark move into the Torchwood storage area, battling another force of Cybermen. Some human soldiers break in and add to the chaos. The Doctor stumbles into the area as well, grabbing two magna-clamps before leaving. As the Daleks blast their way through all opposition, the new Cyber-Leader calls for reinforcements, commanding all Cybermen to report to the tower. Dalek Sec overrides the roof mechanism, and elevates upward with the Ark. As the Doctor and the others watch, the Ark opens above London and starts spinning, disgorging Dalek after Dalek. The Doctor realises that the "Time Lord science" Dalek Sec referred to was the fact that the Ark is bigger inside than outside: the Ark is a prison ship, containing millions of Daleks. As hundreds of Daleks line up in aerial formation, an army of heavily armed Cybermen appears and attacks the Daleks. The Daleks and Cybermen begin fighting all over the world, with the human race caught in the crossfire.

Pete believes the situation to be hopeless, and prepares to escape back to his world while offering to take Jackie along with him. The Doctor, however, is more optimistic. Wearing his 3-D glasses, he explains that it allows him to see that everything that has crossed the Void between universes has picked up background radiation from it: "Void stuff". Since the Daleks and Cybermen have been hiding in the Void, they will be saturated in it and will be pulled back into the Void if he re-opens the rift, which will then collapse in on itself and seal the breach between worlds.

Rose, however, points out that they are covered in "Void stuff" too. The Doctor explains that he will open the breach here, but if Rose and the others go back to Pete's world, they will be safe. The Doctor will hang on to the magnetic clamps so he will not be pulled in. Rose realises that if the breach seals she will never be able to return and refuses to leave the Doctor despite the prospect of never seeing her mother again. While Rose and Jackie argue about who is leaving, the Doctor and Pete slip the devices around their necks and Pete transports them all across. However, Rose reactivates her device and returns, telling the Doctor she will never leave him. Pete stops Jackie from returning too, telling her that every time they cross the breach they damage both worlds.

Rose sets all the coordinates on the Void controls to six on the Doctor's instructions. As the Cybermen climb the stairs intending to use the breach to retreat to and retake Pete's world, they are met by a Cyberman with a female-sounding voice, that of Yvonne Hartman. She declares that they shall not pass and shoots them with an energy rifle. As she repeats that she did her duty for Queen and country, a tear of oil leaks from the duct below her left eye.

The Doctor and Rose fix the magnetic clamps on the walls. When they open the breach, Dalek Sec senses the breach is active, deduces that the Doctor is behind it, and sends a squad of four Daleks to exterminate him. Rose and the Doctor pull the levers, activating the breach, holding on as tightly as possible to the clamps. Outside, the Daleks released from the Ark and even the Ark itself are drawn towards Torchwood Tower and are rapidly sucked into the breach. The Cybermen, still firing at the Daleks, are also pulled upward into the sky. However, Dalek Sec (along with the rest of the Cult) initiates an emergency temporal shift and escapes.

The power lever on Rose's side begins to shift to the off-line position, threatening to abort the process while there are still Daleks left. Unable to reach her lever while still holding on, Rose lets go of her clamp to do so. She pushes the lever back up and power is restored, but Rose is left clinging on as the Void tries to consume her. The Doctor yells at her to hold on.

As the last of the Daleks fall into the breach, Rose can no longer hold on and lets go, flying towards oblivion. The Doctor screams in anguish, but at the last moment, Rose is saved by Pete who materialises in front of the breach, grabs her and vanishes again. The breach ripples, and seals itself leaving Rose trapped in Pete's world. On the parallel world, Rose beats the wall, sobbing hysterically, as Pete notes that his device no longer works. On both sides of the breach, the Doctor and Rose lean against the wall, resting their cheeks against it for a moment. The Doctor then walks away sadly, alone.

Some time later, Rose has a dream where she hears the Doctor's voice calling her. Rose, Jackie, Pete and Mickey follow the voice to a deserted beach fifty miles outside Bergen, Norway, on the coastline of Dårlig Ulv Stranden, which roughly translated is Bad Wolf Bay. There, an image of the Doctor appears; he tells Rose that he found the last of the breaches, and is transmitting the signal by using the TARDIS to harness the power of a supernova, commenting that he is burning up a sun to say goodbye. Rose tells him that he looks like a ghost, and the Doctor increases the image of himself to maximum projection — making it look as if he is really standing there, but he regretfully tells Rose that he is still just an image, and that she cannot touch him. With only two minutes left, the two share their final farewell. Rose tells the Doctor that her mother is three months pregnant. At first, Rose jokes that she is now back working as a shop girl, but then reveals that she is with the parallel Torchwood, which has re-opened, as they could use her expertise with aliens. The Doctor smiles proudly and says, "Rose Tyler: Defender of the Earth."

The Doctor tells Rose that she is officially listed among those that died on that day. Rose tearfully asks the Doctor if she will ever see him again, and the Doctor replies regretfully, "You can't." Breaking down, Rose asks what the Doctor will do, and he says he will go on, alone. Weeping, Rose tells the Doctor she loves him. As it is his last chance to do so, he begins to reply, "Rose Tyler..." but his image fades. Rose, still in tears, turns and runs back into Jackie's arms.

In the TARDIS, the Doctor stands for a minute, lips still parted, and a single tear rolls down each cheek. He takes a deep breath to help him regain his composure and regretfully starts to work the console again. Suddenly, he looks up to see a woman in a wedding dress standing in the console room. Dumbfounded, all the Doctor can repeat is, "What?", as the bride demands sharply that he tell her where she is and "what the hell" the place is...

Cast

 * The Doctor - David Tennant
 * Rose Tyler - Billie Piper
 * Jackie Tyler - Camille Coduri
 * Mickey Smith - Noel Clarke
 * Pete Tyler - Shaun Dingwall
 * Jake Simmonds - Andrew Hayden-Smith
 * Yvonne Hartman - Tracy-Ann Oberman
 * Dr Rajesh Singh - Raji James
 * Cyber Leader - Paul Kasey
 * Dalek/Cybermen Voices - Nicholas Briggs
 * Dalek Operators - Barnaby Edwards, Nicholas Pegg, Stuart Crossman, Anthony Spargo, Dan Barratt, David Hankinson
 * and introducing Catherine Tate as the Bride

Uncredited cast

 * Cyberman - Jon Davey

Daleks

 * Dalek Sec is leader of the Cult of Skaro. The other members are Dalek Caan, Dalek Thay and Dalek Jast.
 * The Cult perform an emergency temporal shift.
 * The Daleks use rels to measure time.
 * The imprisoned Daleks are freed from the Genesis Ark.

Species

 * The Cybermen attempt to negotiate with the Daleks.

Gallifreyan artefacts

 * The Genesis Ark can only be opened by a time traveller.

Conflicts

 * The events of this episode come to be known as the Battle of Canary Wharf.
 * The Doctor states he was on the front lines at the Fall of Arcadia, and that he may one day "come to terms with that".

Individuals

 * Harriet Jones is President in the alternate Earth London.
 * Rose Tyler now calls the parallel Earth's Pete Tyler "Dad".
 * Jake gives instructions to Chrissie, another member of the Preachers.

Bad Wolf

 * The Doctor and Rose say their final goodbyes at Dårlig Ulv Stranden, which translates as Bad Wolf Bay.

Story notes

 * The working title for this episode was Torchwood Falls.
 * This is the final episode where the control room of the TARDIS is dimly lit.
 * Doomsday and the 2006 World Cup finale aired in the same week. Radio Times did variant covers of a team of a Cybermen and a team of Daleks on a football pitch, the lead holding a football.
 * Julie Gardner, the executive producer for the new series, said that the Doctor was going to "say it back"; he gets another chance in Journey's End.
 * Besides resonating throughout Series 3 and into Series 4, the events of Doomsday, or specifically Rose's fate, would be referenced in two original songs related to the series: the extended version of "Song for Ten" recorded for the Series 1 and 2 soundtrack album, and "Love Don't Roam", which would be introduced during the next episode, The Runaway Bride.
 * The music that plays after Rose is sealed off in Pete's Universe (titled Doomsday) is the same music heard when the Ninth Doctor first shows Rose the TARDIS in Rose.
 * This is the only finale in the revived series written by Davies that features the Tenth Doctor but not Captain Jack Harkness.
 * According to commentaries and discussion on the Series 2 DVD release, secrecy was very tight surrounding the filming of the two final scenes of the episode. According to Tennant and Davies, only Tennant and Piper were given the script for their farewell scene in advance, with the director receiving his copy soon before filming. According to Tennant, the filming of the Catherine Tate cameo was a rare example of a surprise being kept without getting spoiled; the scene was shot with minimal crew while the rest of the production team were having their wrap party. As such, the Tate scenes were actually shot long after the Doctor and Rose's farewell scene, which was filmed during an earlier production block.
 * At this point, Tate's character is identified only as "The Bride". She wouldn't be officially identified by the name Donna Noble until months later as publicity for the Christmas special began to circulate.
 * Army of Ghosts/Doomsday is the only multi-part series finale written by Russell T Davies not to feature a regeneration scene. The Ninth Doctor regenerates in The Parting of the Ways, the Master regenerates in Utopia, the Tenth Doctor almost regenerates in The Stolen Earth/Journey's End, and then does so for real in The End of Time.
 * This story is marked by one of the few attempts in the television series, modern or classic, to introduce humorous elements to the Daleks; Dalek Sec is uncharacteristically witty for a Dalek, a fact explained in-universe by the special status of the Cult of Skaro. It tells the Cyberleader, "You are superior to us in only one respect...you are better at dying". There are also further comical dialogue between Daleks and a Cybermen throughout the episode. Other examples of humour in Dalek stories can be found in The Chase and Destiny of the Daleks.
 * The episode also introduces some humorous elements to the Cybermen - when the Cybermen state that the design of the Daleks is "inelegant", and the Daleks respond that they have no concept of elegance, the Cyberman drily responds with, "This is obvious."
 * The Doctor tells Rose to set all the coordinates to "6". This would be "666", or the number of the Beast. This further correlated to the story as sending the Dalek and Cybermen to "hell", which is what some people call the Void.
 * The reference to Harriet Jones leading a golden age in the parallel world directly correlates to the Doctor's earlier prediction of Harriet Jones leading three successive terms as a leader in Britain's Golden Age.
 * During the December 17th, 2014 livecast on the Twitch channel TheAdiposeTV promoting the introduction of Big Finish Productions character Charley Pollard in the game Doctor Who: Legacy, Nicholas Briggs, doing a guest interview via Skype, revealed that he disagreed with the way one of Dalek Sec's opening lines was portrayed. In its original form, Briggs thought it sounded as though Sec was asking something to another Dalek, but then answering his own question. He asked episode director Graeme Harper if they could split it into two lines, have Sec turn to the Gold Dalek and ask the question. Nicholas went on to say Graeme agreed, but they had to get special permission to change the script.

Myths

 * Several newspapers reported that the character of Adeola Oshodi, played by Freema Agyeman, would join the Doctor as his new companion at the end of the episode. This was only partially correct; Agyeman did indeed become the Doctor's next companion but as the new character of Martha Jones, who debuted two episodes later. However, Russell T. Davies has gone on record as saying that had he known Agyeman would prove such a perfect choice for a new companion, he would have rewritten the previous episode to have Adeola survive.
 * Rose would die because she said this was the story of how she died. She didn't die.

Ratings

 * 8.22 million (UK final)

Production errors

 * When Rose answers her phone as the Doctor is calling her, the display on the phone indicates that the call has been connected for 56 seconds.
 * When the Dalek shoots the Cybermen for proposing an alliance, the dead Cybermen land on a black floor close to the Dalek. In the shots before the ground was beige and the Dalek was further away (this is due to pre-filmed footage from the fight in the sphere room being used flipped).
 * Thay, Jast and Caan's recognition codes switch between shots.
 * The fires outside London are not present when the Daleks fly out of the Genesis Ark.
 * In the ending scene after the Doctor has faded and Rose is hugging her mum, if you look at the back wheel of the jeep in the background a foot steps out from behind the wheel and then steps back.
 * Although great pains were taken to keep David Tennant's hair from blowing in the wind during the last scene since he's supposed to just be a projection, you can still see his hair moving slightly. Also, the projection's hair does not match his hair in the TARDIS.
 * When the Daleks shout, "Exterminate" when they burst through some doors to fight forces of Cybermen, their lights do not flash when they speak.
 * One of the Cybermen that alerts the Cyber-leader of the "unknown technology", has the Cybus "C" on its chest on backwards/upside-down.
 * When the Daleks identify their names, Dalek "Thay" says his name at the start, but it is actually Dalek "Jast"; in the shots before this part you clearly see that "Thay" is behind "Sec", so if it was the real names it would be, "I am Dalek Jast, Dalek Sec, Dalek Jast, Dalek Caan".
 * At one point in the battle between the Daleks, Cybermen, Torchwood and the Preachers, a Dalek fires, narrowly missing a Preacher standing up and hitting a CGI Cyberman whose hand lands on the crouching Preacher. As it falls, being CGI, it causes no effect on the Preacher.

Continuity

 * The Tenth Doctor mentions that he was present at the Fall of Arcadia. Ironically, his incarnation would get to be present for the battle in spirit while it was underway. The instance took place after being made to revisit it through a projection cast by the Moment, once it had let him back into the Time War by using its immense powers to breach the time lock he had placed on its events in a previous incarnation. Through this, the Tenth Doctor's statement became literally true. (TV: The Day of the Doctor)
 * The Doctor mentions how a Dalek screams. His ninth incarnation previously made a Dalek scream by torturing it. (TV: Dalek)
 * The Doctor wears his 3D glasses. (TV: Army of Ghosts)
 * Several companions have departed in Dalek stories: Susan, (TV: The Dalek Invasion of Earth) Ian Chesterton and Barbara Wright, (TV: The Chase) and Tegan Jovanka. (TV: Resurrection of the Daleks)
 * Adric also departed in a Cybermen story. (TV: Earthshock)
 * There is a flashback sequence to the events of TV: Dalek, displaying how Rose touched a Dalek.
 * Rose refers to the events of TV: The Parting of the Ways, specifically how she killed the Dalek Emperor.
 * Daleks and Cybermen would later appear together in TV: The Pandorica Opens. Coincidentally they do form an alliance in The Pandorica Opens despite refusing to in this episode, and have entered an alliance in the past in AUDIO: The Ultimate Adventure.
 * Dalek Sec comments on the war that they had declared on the Cybermen, "This isn't war; this is pest control!" mirroring Commander Skorr's comment, "This isn't war; this is sport!" (TV: The Poison Sky)
 * Dalek Sec says "we would destroy the Cybermen with one Dalek", which is reminiscent of what another Dalek once said to Mavic Chen: "One Dalek is capable of exterminating all!" (TV: The Daleks' Master Plan)
 * The Daleks deduce what the Cybermen are by noticing their similarities with the variants in their universe. (TV: The Tenth Planet, et al.)
 * The Cybermen being vulnerable to rocket-launchers was first shown in TV: The Invasion.
 * Off-screen during this conflict, Torchwood One operative Lisa Hallett is captured by the Cybermen and partially cyber-converted, but another operative, her boyfriend Ianto Jones, rescues her and flees the Battle of Canary Wharf. Left without elsewhere to go, he will later try to reestablish his roots with the Torchwood organisation in Cardiff by attempting to win favour with Torchwood Three leader Jack Harkness. Eventually, he proves his worth and Jack takes him in. (TV: Fragments) However, though Ianto cares dearly for this new team, he will secretly harbour his girlfriend in Torchwood Three's base, hoping her conversion can be undone. This pans out tragically when Lisa fully activates as a Cyberwoman. (TV: Cyberwoman)
 * When the Cyber Leader addresses the world he says, "You will become like us". This is not dissimilar to a line spoken by the Cyber Controller on Telos: "You will be like us". (TV: The Tomb of the Cybermen)
 * When the Tenth Doctor sends Rose to Pete's World, she says, "He's not doing that to me again," referring to when the Ninth Doctor sent her on a one-way trip home to protect her, before returning. After later being trapped in Pete's World, Rose tearfully and hopelessly screams, "Take me back! Take me back!" the same words she used when the TARDIS had been taking her home. (TV: The Parting of the Ways)
 * The Doctor mentions being at Pete and Jackie's wedding and how Pete fumbled her name. (TV: Father's Day)
 * Pete Tyler mentions how his wife died. (TV: The Age of Steel)
 * While only Dalek Sec is shown to use an emergency temporal shift to escape, it's later revealed the whole Cult of Skaro escaped in this manner. They later return as the main enemies of the series 3 story Daleks in Manhattan/Evolution of the Daleks. The Cult of Skaro storyline presumably concludes in Journey's End with the apparent death of Dalek Caan.
 * The Doctor mentions that the Eternals called the void "the Howling". (TV: Enlightenment)

DVD releases

 * This episode was released as a "vanilla DVD" together with Army of Ghosts and Fear Her on 25 September 2006.
 * This episode was also released as part of the Season 2 box set. Due to scheduling decisions made by the show's Canadian broadcaster, the CBC, the North American release of the box set occurred several days before Doomsday was broadcast in that country.