Turn Left (TV story)

"It's coming, Donna. It's coming from across the stars and nothing can stop it..."

- Rose Tyler

Synopsis
Donna's entire world collapses, but there’s no sign of the Doctor. Instead, she finds help from a mysterious blonde woman - a traveller from a parallel universe. But, as Donna and Rose Tyler combine forces, are they too late to save the whole of creation from the approaching darkness?

Plot
The Doctor and Donna are on the planet Shan Shen, mixing with the locals. Donna wanders away from the Doctor to explore. A mysterious fortune teller tempts Donna with a reading. The fortune teller searches Donna's past for a single event, finally choosing a moment in June 2007, where Donna and her mother are in a car at a T-junction arguing about her future. Sylvia is trying to persuade Donna to turn right and ask businessman Jival Chowdry for a job; but Donna turns left to go to her planned temp job at H.C. Clements. As the fortune teller attempts to persuade Donna to turn right, something crawls onto Donna's back. Finally, under the fortune teller's persuasion, Donna turns right and alters the course of her life as well as the future of all existence.

It is Christmas Eve 2007, but in an alternate world where Donna, who now never worked for H.C. Clements, has never met the Doctor. The Racnoss Webstar attacks London, and is destroyed by the army, at a terrible cost: near an ambulance and a group of UNIT trucks, Donna overhears a UNIT officer telling someone that they found a body. The Doctor's body. As Donna walks away, a blond figure suddenly appears: the Doctor's former companion Rose Tyler comes running down the street and asks for information about the body that has just been bundled into the ambulance. Rose is stunned to hear that it was the Doctor.

In April 2008, Donna is fired from her job in the photocopying firm. Meanwhile, the Royal Hope Hospital is mysteriously transported to the Moon. When it returns, there is only one survivor: a medical student named Oliver Morgenstern, who relates the terrible events. As in the original timeline, the hospital had been moved by the Judoon and infiltrated by a Plasmavore. Sarah Jane Smith (at the hospital with her son Luke and his friends Maria and Clyde) attempted to fill the Doctor's role, and did manage to stop the MRI machine from irradiating the Earth--but, without the Doctor, the humans couldn't find a way back to Earth, and all suffocated. Medical student Martha Jones gave Morgenstern the last oxygen tank so that someone would survive to tell the story.

As Donna digests the terrible news, Rose reappears, and warns her to leave London for Christmas 2008.

Donna takes Rose's advice, and treats her mum and grandfather to a Christmas holiday in the English countryside. On Christmas morning 2008, they watch in disbelief as a replica of the Titanic is reported to be heading straight for Buckingham Palace. The three run outside and watch, horrified, as a mushroom cloud rises above London.

Like many other refugees from London (and southern England, which was irradiated), the Nobles are forced to move to Leeds, since nuclear radiation from the crash showered over London. They are allocated a house that is shared with two other families.

In 2009, The United States pledges to help Britain with monetary relief but must abandon the plan when their own crisis strikes: 60 million of their population are turned into Adipose. Since London no longer exists, Adipose Industries had targeted the USA.

Some time later, Donna finds soldiers gunning at cars when the Sontarans activate the ATMOS devices, covering the Earth with a poisonous fog. A soldier again notices something on Donna's back and holds her at gunpoint, but is released when nothing is apparently there. That night, Donna meets Rose for a third time. Rose explains that the Torchwood team, aboard the Sontaran ship, are trying to stop the catastrophe. Suddenly, the sky is cleared by an atmospheric converter. However Gwen Cooper and Ianto Jones had given their lives to achieve this, while Captain Jack Harkness has been stranded on the Sontaran homeworld.

Rose, who refuses to tell Donna her name and will say only that she has "crossed reality", tries to explain that Donna had saved the Doctor's life in an alternate timeline, though Donna insists that she had never met him. Rose warns Donna about the coming "darkness" that threatens every single universe. Donna tries to walk away, but Rose then tells Donna that she will have to go with her when she is ready and that she has three weeks to decide. Rose warns Donna that when she comes with her, Donna will die. Then she disappears.

Three weeks later, the genial Italian family in Donna's house is evicted as England is now "only for the English". Since the oceans are closed off, they must be taken to a "labour camp". Wilfred says "That's what they called them last time.", alluding to the concentration camps of World War II. Later at night, Donna and Wilf talk about recent events. He notices that the constellation of Orion has gone, though there are no clouds. As the stars disappear throughout the sky, Donna realizes that Rose must be correct. She finds the younger woman, and tells her that she is ready.

Rose takes Donna to a UNIT base and shows her the TARDIS--salvaged from beneath the River Thames--which is dying following the Doctor's death. Using technology researched from the TARDIS, Rose switches on a light which reveals what is on Donna's back: a 'Time Beetle'. Rose explains that it "feeds off time by changing time" and that it is in a state of temporal flux and cannot be removed. Rose goes on further to state that Donna herself is also in a state of flux and has been since her birth. Donna is horrified and the light is turned off. In order to set things right, they prepare to send Donna back in time to stop her past self from turning right. Donna agrees to go, and is elated by the belief that rather than dying, "this whole world [will] blink out of existence [but] a better world takes its place." To this Rose remains silent.

Donna successfully lands back in June 2007, but realizes that she is a half a mile away from her past self and has only got four minutes to save the world. She tries to run to herself, but realizes that she will not make it in time. Donna realizes what Rose meant about her death and throws herself in front of a van; the fatal accident quickly causes a traffic jam that prevents Donna's past self from turning right. Right before she dies, Rose appears and whispers something into Donna's ear to tell the Doctor.

As the original timeline reasserts itself, Donna regains consciousness in the fortune teller's stall on Shan Shen. The frightened and baffled fortune teller flees, saying that Donna's will was "too strong."and first saying "what are you?", but then screaming "what will you be?!". The Doctor enters and an emotionally spent Donna collapses into his arms.

Upon examining the beetle, The Doctor tells Donna that it is part of the Trickster's Brigade and that normally it affects one person and the universe compensates (as what happened to Sarah Jane Smith), but in Donna's case, it created a parallel universe. The Doctor then muses on all of the unique coincidences surrounding Donna: the fact that she had two parallel worlds that formed around her (this one and the one in the CAL computer) and the fact that he's met her and  her grandfather twice. The Doctor concludes that they seem to be somehow linked. Donna tells the Doctor she is nothing special, but he counters saying that she's "brilliant". Hearing that trigger's Donna's memories of Rose on the parallel world and she starts to relate Rose's warnings to the Doctor. When asked if she remembered the blonde woman's name, Donna said she was never told it, but Donna does tell the Doctor the two words the blonde woman whispered into her ear: "Bad Wolf". Horrified, The Doctor runs out into the market square to see the words Bad Wolf everywhere; on posters pasted onto the walls, on the ceremonial flags hanging over the market, even on the TARDIS itself. Inside the TARDIS itself, the control room is glowing red and the Cloister Bell is ringing ominously. When Donna asks what's going on, the Doctor replies, "It's the end of the universe."

Cast

 * The Doctor - David Tennant (Brief)
 * Donna Noble - Catherine Tate
 * Rose Tyler - Billie Piper
 * Wilfred Mott - Bernard Cribbins
 * Sylvia Noble - Jacqueline King
 * Mr Colastanto - Joseph Long
 * Captain Erisa Magambo - Norma Dumezweni
 * Fortune Teller - Chipo Chung
 * Mooky Kahari - Marcia Lecky
 * Veena Brady - Suzann McLean
 * Alice Coltrane - Natalie Walter
 * Private Harris - Clive Standen
 * Jival Chowdry - Bhasker Patel
 * Oliver Morgenstern - Ben Righton
 * Spanish Maid - Loraine Velez
 * Trinity Wells - Lachele Carl
 * Studio News Reader - Jason Mohammad
 * Housing Officer - Sanchia McCormack
 * Soldier Number 1 - Lawrence Stevenson
 * Soldier Number 2 - Paul Richard Biggin
 * Man in Pub - Neil Clench
 * Female Reporter - Catherine York
 * Woman in Doorway - Terri-Ann Brumby
 * Tish Jones - Gugu Mbatha-Raw (Uncredited)

Production crew
to be added

Events in the alternate timeline

 * The Doctor drowns and does not regenerate whilst defeating the Empress of the Racnoss under the Thames.
 * Private Harris was at the scene when the Doctor's body is recovered from the Thames Torchwood complex.
 * Martha Jones, Sarah Jane Smith, Maria Jackson, Luke Smith, Clyde Langer all die in Royal Hope Hospital when it is transported by the Judoon to the Moon.
 * The Titanic crashes into Buckingham Palace killing everyone in the greater London area and contaminating southern England - bar Devon & Cornwall - with radiation.
 * The destruction of London triggers a societal collapese in Great Britain, which becomes a police state that closes its borders and reintroduces concepts such as concentration camps.
 * The March of the Adipose occurs in America instead of the UK; without the Doctor to stop it, tens of millions are killed, preventing the US from aiding Great Britain and accellerating the UK's decline.
 * Gwen Cooper and Ianto Jones die whilst assaulting the Sontaran warship. Captain Jack Harkness is transported to Sontar.
 * Although the Sontaran invasion is thwarted, there is no one to prevent the ATMOS devices from decimating the population of the earth, although the UK is spared this as due to the destruction of London ATMOS never came into widespread use.
 * Non-UK citizens are either deported or placed in camps (exactly which is left unclear).
 * Rose Tyler appears to be working with UNIT.

Story notes

 * This is the first story to feature Rose in a starring role since DW: Doomsday.
 * Billie Piper was seen at the end of Partners in Crime, as well as a short cameo in The Poison Sky and another in Midnight. The Partners in Crime cameo was filmed during production of Turn Left, as was the short piece of footage used in Midnight and The Poison Sky. This means no less than three directors would have been at work on the Doctor Who set during the production schedule of Turn Left - the main episode's director, Graeme Harper, the director of Partners in Crime, James Strong, and the director of Midnight, Alice Troughton.
 * Unusually, the episodes festuring Piper were filmed relatively early in the production of the season, which allowed a clip of Rose from this episode to be included in the cinema trailer released in advance of the season being broadcast.
 * Chipo Chung last appeared in DW: Utopia as the Malmooth, Chantho. She plays the fortune teller in this story.
 * This is the 'Doctor-lite' episode of the series, similar to Love and Monsters and Blink, albeit with a much darker storyline. Unlike previous Doctor-lite stories, however, the focus is given to the companion, rather than her also taking a minor role. They used the same scheduling trick in the previous episode, Midnight, which featured virtually no Donna Noble.  These episodes allow the production team to complete fourteen episodes (including the Christmas episode)  in a schedule originally designed to complete thirteen.  A second team can be filming the "extra" episode, with the main cast filming only a day or so.  Their footage is judiciously spread through the episode to give the impression of a larger interaction.
 * A reference to something on Donna's back was last heard in The Fires of Pompeii when Lucius Petrus Dextrus saw into the future.
 * In Doctor Who Magazine it said that Donna will receive a free tarot card reading and find out something bad is going to happen. When she is receiving it there will also be something behind her lurking in the curtains. The Tarot person will also look for a specific event in Donna's past. The episode, as broadcast, takes place on a Chinese-influenced alien world with no reference to Tarot.
 * "The bees are disappearing" is quoted again in this episode, this time by Donna's mother, Sylvia Noble. This is a real-world phenomenon, called Colony Collapse Disorder, the incidence of which increased sharply in late 2006, and the cause of which has not been identified.
 * A recurring theme in previous episodes hinted that Donna would die in the future which occurs in this episode. However, this was an alternate reality Donna who sacrificed herself in order to prevent her past self from taking the wrong turn thus forcing her to meet the Doctor as was planned.
 * Part of this episode is filmed in China Town, though not the one in London, but recreated in Cardiff. Chinese people living in South Wales were invited to be background extras via Facebook at the end of 2007. They had to reply to the Doctor Who casting crew with their name and sizes for costumes to be made for them and they were paid approx £70 for the day. David Tennant was seen in 'China Town' when he took time out of filming though staying on location to appear on Blue Peter to appeal to viewers to donate shoes to their Shoebiz appeal.
 * Donna is told she can have her fortune told for free because she has red hair. This is a reference to Chinese culture, since red is considered very lucky in China.  It's also a common carny trick to draw people into the attraction; half off for lovely ladies, men wearing hats, anything that matches some characteristic of the person being appealed to.
 * Graeme Harper's penchant for including a distorted image of a main character is present in this story.  Though not included in  every single episode he's directed for BBC Wales, it's seen often enough in the majority of his stories to be considered something of a directorial "signature".  More typically achieved through the use of refraction (The Unicorn and the Wasp, Army of Ghosts, Journey's End and Utopia), here the motif is continued through the use of reflection.  The theme of Donna's multiple worlds is caught through the simple use of mirrors, much as the notion of investigation was conveyed by the use of magnifying glasses in earlier stories.
 * According to Russell T Davies on Doctor Who Confidential this episode is the "cheap episode", as he wanted the TARDIS to be on fire, but the budget didn't allow for the effect.
 * A variation of 'The Wall Theme', (The Wall Theme is a variation of Rose's Theme, played in Doomsday.) with added guitar parts, is played before Donna is sent back in time.
 * Two pieces of background pop music return from other episodes. In the scene in which Donna goes out with her friends to celebrate her new job at Chowdry's personal assistant, the song "Merry Xmas Everybody" by the glam rock band Slade can be heard. This was also playing during Donna's wedding reception in The Runaway Bride.  Later, the song underscoring the Noble family's arrival at Firbourne House for their raffle-won holiday is the same rock version of "Rudolph the Red-Nosed Reindeer" first heard on Mickey's radio in the The Christmas Invasion ' s teaser.
 * Billie Piper states in the accompanying Doctor Who Confidential episode that she had forgotten how to play Rose, and needed to watch past episodes to remind herself.
 * This isn't the first time a Doctor Who story has examined a "What if..." scenario involving the Doctor's influence on a person's life. A similar storyline involved Eighth Doctor companion Samantha Jones, depicted in two wildly diverging timelines (EDA: Unnatural History).
 * The revelation that the events leading to the creation of the alternate timeline originated from The Trickster is a direct reference to a character from The Sarah Jane Adventures and, indirectly, the events of SJA: Whatever Happened to Sarah Jane? in which Sarah Jane Smith was similarly taken out of time. This marks the first direct crossover between the spin-off and Doctor Who (discounting Sarah Jane's connection to the parent series, of course).
 * At one point the Nobles and the Italian family take part in a singalong to Queen's "Bohemian Rhapsody". This tune has been the basis for two practical jokes featured on Who franchise-related blooper reels: a group of Sycorax are shown singing it in the Series 2 blooper reel, while the Series 2 gag reel for Torchwood shows the cast cutting up to the same song.

Ratings

 * Official Broadcast Audience Research Board (BARB) - 8.09 million viewers

Myths and rumours

 * Many fan reviews and discussions of this episode have noted that, for reasons unknown, Billie Piper speaks with a noticeable lisp in many of her scenes - a lisp not present when she was last on the show; a frequently cited example being when Rose tells Donna she's the most important woman in all of creation. Among the speculated reasons as to why is Piper's statement on Doctor Who Confidential (see above) that she had forgotten how to play Rose -- a character who speaks with a more working-class accent than Piper's natural voice. Rose is starting to speak more like the Doctor himself as she has become more like him in the sense of using technobabble and not wishing to accept salutes, nor does she reveal her name. The lisp is present, but less noticeable in the next two episodes and appears to be less noticable (if not missing completely) in interior studio scenes as opposed to on-location filming. Also, the lisp is not present at all in Piper's Doctor Who Confidential interviews shot during production of the final three episodes, nor is it heard during the instalment of David Tennant's Video Diaries pertaining to the production of The Stolen Earth/Journey's End in the Series 4 DVD box set.
 * The opening credits are reversed, showing the TARDIS moving in the opposite direction in the time vortex. As broadcast and released to DVD, the opening credits are presented normally.

Filming Locations
to be added

Discontinuity, Plot Holes, Errors

 * If Donna never appers inside the TARDIS in The Runaway Bride, what draws The Doctor's attention to The Racnoss? Maybe the job as a temp at H.C. Clements would have gone to another woman and Lance, who would have already been working there, would attract this woman and feed her the huon particles instead and she could have possibly (like Donna) fell in love with Lance consequently leading to their marriage resulting in "The Runaway Bride" happening all over again except with the other woman (who was employed instead of Donna) as the Bride who is dragged into the TARDIS on her wedding day by the huon particles. This woman may not have had the strength or the courage to continue on with the Doctor to try and defeat the Racnoss in the Torchwood lab under the River Thames therefore, the Doctor would not have had anyone to stop him subsequently ending in his death...Or maybe it was just the giant Christmas Web Star destroying London that drew the Doctor's attention.
 * In Voyage of the Damned, its stated that everyone except the queen and wilf have left london, so why is everybody dead when the titanic hits the earth??? Possibly because they've not gone far away enough to avoid the blast/radiation etc. Roughly how many nuclear bombs would an exploding nuclear storm be worth?, Also, everyone leaving could have been influenced by the master confirming aliens, which wouldnt have happened in this timeline, as Yana wouldnt have been reminded.


 * The Doctor died in Donna's World, but he survived in the real world, so shouldn't he still be able to stop the reality bomb with the real Donna?


 * The stars were going out in the alternate reality, but would the Doctor be dead so he wouldn't have been able to stop the Final Experiment so it would have gone through and Dalek Caan wouldn't have gone and rescued Davros. It was said in the main reality that the blast would spread to all realities


 * The sound and shaking of the Royal Hope disappearing is heard before it actually vanished, whereas in Smith and Jones the sound was heard during the incident.


 * How is it possible for the Doctor to die too quickly to regenerate? It is possible that Time Lords cannot regenerate from everything. The Fifth Doctor was worried about his regeneration in The Caves of Androzani.  Also, River Song in Forest of the Dead outright stated that there were things that even the Doctor couldn't regenerate from. As an added note, how is it possible for the doctor to regenerate at all, very little is known about the actual process, and its weaknesses


 * The Doctor revealed that the Nuclear Storm drive would wipe out all life on Earth. This is incorrect as it only destroys London. Someone on the ship could have prevented it having such a bad effect. Astrid may not of died without the need to protect the Doctor.


 * Why would an emergency government, greatly limited in funds already, install the probably expensive ATMOS in all its vehicles? They'd have to be cheap so that as many people get them as possible. Donna said they were cheap in Partners in Crime


 * Why is Captain Jack transported to Sontar? The lack of explanation may mean that it will be explained in some later episode. It may even be explained in Torchwood, since he is immortal he would be the perfect soldier for the Sontarans. It's also possible that Jack wasn't able to destroy the Sontaran ship and was captured.


 * Why isn't the planet ruled by Carrionites if the doctor wasn't alive to stop them? The beetle was part of the Trickster's brigade - perhaps the Trickster stopped those invasions. It is also possible that Shakespeare was able to defeat them on his own, as The Doctor often comments on the Bards remarkable ability to grasp what was happening.


 * Donna looks at the sky and the stars were disappearing. It is also revealed the same happened in Rose's universe. If the stars got destroyed, it would take many years at the speed of light for the people of Earth to begin seeing the stars disappearing, and the stars would disappear very very slowly over many many years. By that time Earth would be destroyed before anyone can see it coming. This also leads to a big plot hole in later episodes as to why Rose began to search for the Doctor. Could The Darkness be something that destroys not only the stars but also (or conceivably even rather) the light as it travels to Earth? If the Reality bomb cancels out Atoms, as said in Journeys End, stars would be some of the first to go as their atoms are widespread, whereas earths are compact(stars are gas or plasma, and earth is solid and liquid.


 * It's established that (at least prior to the March of the Adipose) the UK is the only part of Earth in dire straits after the "Titanic" crash. Why, then, don't the Nobles, and their friends, simply leave the country? It's established that some countries have closed their borders, so presumably others did the same. Also, it still takes money to travel, something the Nobles and friends do not have. And it's also established that restrictions on movement have been established, suggesting they couldn't leave if they wanted to.
 * What about the Lazarus creature? After Smith and Jones the next 'present day' episode is The Lazarus Experiment. Surely the Lazarus creature would have attacked the people of London without the Doctor to stop him? It would not have happened. The Lazarus Project formed part of a plan by Harold Saxon, aka the Master, to trap the Doctor and Martha. With the Doctor dead, Professor Yana would not have reverted to the Master.
 * It is never explained in this or either of the following episodes how Rose was able to manifest the Bad Wolf imagery. Possibilities include residual effects of Rose being exposed to the time vortex back in The Parting of the Ways, including the possibility the appearance of "Bad Wolf" might have originated from Rose's original scattering of the message in that episode (since she saw both the future and the past when she gaved into the vortex. Since Donna doesn't appear to react to the sudden appearance of the words, it's also quite possible this is some sort of hallucination experienced by the Doctor. Or maybe it is Rose's connection with the TARDIS. She was able to make the TARDIS translate all words to BAD WOLF
 * In Donna's universe, the Adipose still came to Earth. In this universe, the Adipose breeding planet would not have been lost (not stolen by the Daleks) and they would have no reason to come to Earth.

Continuity

 * This is the second time Rose was present at the death of someone she knew, whom also ultimately died to correct the timeline. In DW: Father's Day, Rose was present at her father's death, which she prevented when she had come back in time with the Doctor. The resulting fracture of creating a parallel world caused chaos until that parallel Peter Tyler sacrificed his life to restore the original timeline. In this episode Rose is present at parallel Donna's death, which caused the younger Donna to turn left instead of right, restoring the timeline. Ironically, both parallel versions of Peter and Donna are hit by a car, and both die with Rose by their side.
 * Among other uses of the phrase "Turn Left" in the series: In DW: The Sontaran Strategem the ATMOS kept saying Turn Left; Captain Jack mentioned telling someone they should have turned left during a joke in Boom Town; Events leading to an alternate future, were due to people 'turning right' instead of 'turning left' in TWN: The Twilight Streets.
 * Like the TARDIS, Donna's car is blue. She often is seen wearing blue, and when leaving her job, she decides to keep a blue hole-punch, notable since for most of the series, the Doctor has been inadvertently punching holes in the fabric of the universe.
 * Bad Wolf returns as a warning for the end of the universe. Bad Wolf was last heard in DW: ''Doomsday' (Although the TARDIS had turned Red at the end of 'Turn Left' to warn the Doctor of 'The End Of The Universe' so the TARDIS could have used 'Bad Wolf' as another warning after Rose used it in 'The Parting Of The Ways'.)
 * The Cloister Bell is heard, again as a warning, it was last heard in DW: Time Crash.
 * Two phrases said by Lucius Petrus Dextrus in DW: The Fires of Pompeii come to fruition in this episode: "There's something on your back" and "She is returning".
 * The characters from The Sarah Jane Adventures are named in the news report to be dead in the parallel timeline.
 * A UNIT soldier refers to regeneration. UNIT has extensive knowledge of regeneration, having directly been involved with the aftermaths of the regenerations of the Second Doctor and Third Doctors, plus The Brigadier himself is known to have met most of the Doctor's incarnations (both on screen and in the spinoffs), and UNIT was also involved with the newly regenerated Tenth Doctor in The Christmas Invasion.
 * In DW: The Sontaran Stratagem, Colonel Mace and Captain Price saluted the Doctor but he said 'Don't salute, please'. When Captain Magambo saluted Rose, she told her not to salute as well. The difference is that this time Donna doesn't ask for a salute like she did in The Sontaran Stratagem.
 * There is some similarity (in that they both hang invisibly on the back) between the time beetle and the spiders in (DW: Planet of the Spiders).
 * Mirrors have been used for time travel in DW: The Evil of the Daleks and BFA: The Time of the Daleks.
 * Mirrors were also used to expose and reveal the Mara (as is used to reveal the beetle) in DW: Kinda, and a mirror was essential to the storyline of NDA: Martha in the Mirror, and, in a sense, of DW: Timelash.
 * "The Bees are disappearing" is spoken again in this episode, this time by Sylvia Noble. The quote has been used several times throughout the series, usually spoken by Donna. It is interesting to note that at the end of Turn Left, the "fortune teller" says to Donna, "What will you be?". This is used in the wrong context. In correct grammar she should have said "What will you become?". Therefore by saying 'be'she may again be referring to bees, and that Donna may have some future connection with them or their dissapearance. More likely, the sentence "what will you be" refers to the metaphorical sense of becoming a new type of being, as opposed to the act of the change. In this context, the grammar is correct, or that simply, The Fortune Teller was simply talking in modern vernacular. Actually it was literal, Donna becomes half time lord.
 * There have been a few other instances of the Doctor 'dying' and events taking different courses (NA: Blood Heat, DWM: Final Genesis'').
 * In Army of Ghosts Adeola lures her colleague to his death by telling him to 'go to the left'.
 * When Donna, Wilf and Sylvia are watching the news report the picture is said to be coming from the Guinevere range of satellites which is the same range as the Guinevere space project first seen in (DW:The Christmas Invasion)
 * Discounting minor modifications over the years, the replacement of the wording on the TARDIS exterior with "Bad Wolf" -- and this appears to be a physical change given that the words are visible from the inside, too -- marks the first time the TARDIS has been shown undertaking a physical change since Attack of the Cybermen. Although not indicated in dialogue, the fact the TARDIS is now adorned with the words "Bad Wolf" - but the words are gone by the time the vessel returns to earth in the next episode - suggests the chameleon circuit came into play.
 * Rose says to Donna "I'm sorry, I'm so sorry," a phrase often uttered by the Tenth Doctor.
 * The improbability of the Doctor meeting anyone twice by accident is remarked on. Previous examples of such coincidence are the reunion of the Fifth Doctor and Tegan Jovanka in Arc of Infinity after he left her behind in Time-Flight, and meeting Sarah Jane Smith in (DW: School Reunion).

DVD and Other releases

 * Released in the Series 4 DVD boxset in November 2008 along with the rest of the Series.
 * It was released as Series 4 Volume 4 alongside The Stolen Earth and Journey's End.