"I just want you to know there are worlds out there, safe in the sky because of her. That there are people living in the light, and singing songs of Donna Noble, a thousand million light years away. They will never forget her, while she can never remember. And for one moment, one shining moment... she was the most important woman in the whole wide universe."
— The Doctor, saying one of the most heartbreaking goodbyes he ever had to give to a companion.
"But every night, Doctor, when it gets dark, and the stars come out, I'll look up on her behalf. I'll look up at the sky, and think of you."When we last left our heroes, things looked grim. Sarah Jane was about to get gunned down in her car, Gwen and Ianto's More Dakka was not going to cut it and the Doctor was regenerating. Now we're picking up where he left off. Torchwood gets protected by a nifty program Tosh designed, Mickey and Jackie materialise with their BFGs just in time to save Sarah Jane, and Ten regenerates... back into Ten.Wait, what? Apparently, since the Doctor's hand-in-a-jar is kept in the control room, he could use it to heal without changing. He simply directed the excess energy into the hand, instead of into a whole new body. Everyone is relieved that Ten is still Ten (especially Rose, since she came so far and all).The Daleks surround the TARDIS, suck out its power and take them to the Crucible, the Daleks' base ship. Sarah Jane, Mickey and Jackie decide to go along, and some helpful Daleks take them there too.Meanwhile, Commando Martha says goodbye to her mother and teleports to Germany, where we are treated to Daleks speaking German, Martha speaking German and an older woman speaking German - notice the running theme here? She avoids a prophetic woman babbling about nightmares and gets to the Osterhagen station with a mysterious device called the Osterhagen key.The Doctor, Jack, Rose and Donna are surrounded by Daleks in the Crucible and step out of the TARDIS to face them. Donna is distracted by the sound of a heartbeat, and gets stuck inside the TARDIS. The Daleks open up a trap door and the TARDIS gets flushed into the core of the Crucible. Donna is trapped in the burning TARDIS. She looks over at the hand and reaches out to touch it. The jar bursts, and the hand is enveloped in a golden light that seems to be forming... a new body! It's the Doctor!
— Wilfred Mott, trying to comfort the Doctor.
Donna: It's you!The Doctor Clone dematerialises the TARDIS just in time, but everyone else thinks it has been destroyed. Jack lets himself get killed by a Dalek and plays possum, hoping to infiltrate the base. The Daleks take the Doctor and Rose to Davros and sweep Jack into the trash.Back on the TARDIS, the Doctor Clone finds some clothes (specifically, the blue outfit), and tries to explain himself to Donna.
Doctor Clone: Oh yes!
Donna: You're naked!
Doctor Clone: Oh yes!
Doctor Clone: Oh yes!
Donna: You're naked!
Doctor Clone: Oh yes!
Donna: You. Are. Bonkers! Is that what Time Lords do? Lop a bit off, and grow another one? You're like worms!Apparently, when Donna touched Handy, there was a "instantaneous biological metacrisis" and the Doctor Clone grew out of Donna. As a result, he talks a bit like her too.
Donna: Oi! Watch it, space man!More than that, New Ten has only got one heart. ("Oh, that's disgusting.") Apparently, he's part Time Lord, part human. He explains to Donna how special she is for being part of him now and she's finally starting to believe it a little.Back at the crucible, Davros gives the Doctor a briefing on their plan. Apparently all the 27 planets combined form a "reality bomb" that dissolves every form of matter. Davros gets really excited and chews on every available piece of scenery. But the Doctor realises that Davros isn't remotely in charge of his creatures any more. He was taken out of the Time War by Dalek Caan, who stared into Time itself, neatly mirroring the way Rose saved the Doctor from the Daleks once. However, Dalek Caan didn't have a Time Lord around to take Time itself away again, and he went completely mad in the process. Davros is now little more than the Daleks' "pet": a source of DNA cells to rebuild the Dalek race, and locked in the basement by his own offspring. Anyway, Davros explains that the 27 stolen planets form a compression field which can be released as a wave with the power to cancel out the electrical energy of atoms, reducing all matter into dust and then turning the dust into atoms and the atoms into nothing. The resulting "reality bomb" has the potential to keep travelling forever across all universe and even creep its way into parallel universes, destroying all life and matter in existence, until only the Daleks remain.The Doctor's friends haven't given up yet. Jack, Sarah Jane, Mickey and Jackie will use Sarah Jane's Veran necklace (which contains a crystallised nova explosion) to blow up the Crucible (including themselves) if Davros doesn't stop. Similarly, Martha Jones will use the Osterhagen key to activate a doomsday device that will blow up the Earth (including herself) and put everyone out of their misery and leaving Davros stuck with just 26 planets: not enough to power up his reality bomb. Unfortunately, these threats work well with Davros' "The Reason You Suck" Speech, as Davros accuses the Doctor of being a Technical Pacifist while turning his friends into tools of violence. The Doctor remembers all the people who died to save his life during the New Series. Regardless of all that, the Doctor's friends' plans come to naught, as they are immediately zapped to the Vault by the Daleks.Suddenly, the TARDIS materialises and the Doctor Clone runs forward with their new Dalek-killing gun. Then Davros, in true Emperor fashion, shoots lightning out of his hands, and zaps the Doctor Clone and Donna. The reality bomb goes into its final countdown and...Nothing happens.Donna stopped it! Even though she used to not even be able to change a plug, Davros' lightning triggered the other half of the metacrisis: when she activated the energy in the hand, part of her became filled with Time Lord essence. Now in possession of an active Time Lord mind, she's able to come up with Dalek-disabling solutions lightning fast with a huge surge of techno-babble. So that's what the Ood were talking about!
Doctor Clone: Oi! Watch it, Earth girl! Ooh... I sound like you!
Doctor Clone: Oi! Watch it, Earth girl! Ooh... I sound like you!
Doctor-Donna: Did I ever tell you, best temp in Chiswick? A hundred words a minute!As they get into the TARDIS, the Doctor Clone decides that even without their reality bomb, the Dalek empire is still a monstrous threat against the universe, so he tampers with the Crucible's control's panel to unleash a lethal energy feedback that blows up all the Daleks, to the utter horror of the original Doctor, who really doesn't like to be reminded of what he did in the Time War. The Doctor offers Davros a chance to be saved, but Davros chooses to stay behind and die on the exploding Crucible, bitterly cursing the Doctor and naming him "The destroyer of worlds!"All the planets are sent home, but Earth just doesn't make it before the teleportation device gets blasted. So, they decide to turn the TARDIS into an Earth tow boat. In Cardiff, Torchwood Three uses the Cardiff Rift to provide massive amounts of energy. The Doctor properly introduces himself to Ianto and Gwen through their video connection, and he and Rose are happy to see that Gwyneth has a 21st century relative. In Ealing, K9 and Luke provide the supercomputer Mr Smith with all the TARDIS data needed to get the Earth back home. Everyone gathers around the TARDIS core to help fly the Earth back home. (All except Jackie, who isn't allowed near the controls.) Everyone hugs everyone. Donna especially hugs Jack a lot.Sarah Jane heads back home to Luke. The Doctor blocks Jack's teleportation wrist watch again ("I told you: no teleporting). Martha promises to destroy the Ostenhagen key and walks off with Jack (whose story continues in Torchwood, "Day One"). Mickey realises that he's finally done following Rose around and... starts following Martha around. The TARDIS heads back to alternate dimension Norway to drop off Rose and Jackie.Rose doesn't want to leave the Doctor, but the Doctor offers her a nice consolation prize of the Doctor Clone, because the Doctor feels that this version of himself is a bit too genocide-happy (much like he himself used to be) and needs a Rose in his life to cure that. The Doctor Clone is also part human, able to age, and willing to spend his life with Rose from now on. This doesn't sit quite right with Rose yet, so she begs the two Doctors to finally tell her what he wanted to say to her last time, after she said "I love you" to him. The Doctor still Cannot Spit It Out. note The Doctor Clone whispers it into her ear, and although we can't hear it, she's happy enough and responds by snogging him.In the TARDIS, Doctor-Donna is starting to exhibit some problems, as her behaviour becomes hyperactive and she literally can't stop talking or focus on a single matter. Her Time Lord brain is overloading her human body, which, as the Doctor solemnly explains, is the reason why there never has been a human/Time Lord fusion before. There's only one way to save Donna's life. She begs and pleads, but the Doctor takes her into his arms and gently wipes her memories. She can never remember who she was, or anything about the Doctor, or she'll burn up. She goes back to the way she used to be, and she can never know about how much she saved the universe or how amazing she was. The Doctor takes her home, where she turns into her old self... her old old self, loud and crass... And someone's going to have to tell her that she's missed two full years, and that her fiancée and her father are dead, that is, if the memory-wiping was thorough enough to blank out that much. The Doctor tells Donna's mother to be nice to her for a change, bids Wilf farewell and steps out of their lives. (For now.)The Doctor goes off, once again on his own. He takes off his suit jacket, soaked to the brim in rain... just like his morale.
- Ain't Too Proud to Beg: The Doctor offers to do anything to save Donna.Doctor: Put me in her place! You can do anything to me, I don't care, just let her go!
- And Starring: Elisabeth Sladen again.
- Apocalypse How: The Daleks threaten a Class Z omniversal (complete physical destruction of all matter in any form across all possible universes) though it may very well "only" have destroyed a finite number of universes, making the devastation multiversal.
- Ask a Stupid Question...:Jackie: I was pregnant, do you remember? Had a baby boy.
The Doctor: Ah! Brilliant. What'd you call him?
The Doctor: Really?
Jackie: No, you plum. He's called Tony.
- As Long as It Sounds Foreign: A couple of grammar mistakes on the German and while "Exterminieren" is a German word, it's rarely used in that language. Technically, not grammar mistakes; the Daleks are aliens and have, according to the series at least, never spoken German before. A few errors can be allowed.
- Back for the Finale: The episode sees the return of every former companion from the previous four series and many recurring characters. The opening credits list David Tennant, Catherine Tate, Freema Agyeman, John Barrowman, Elisabeth Sladen and Billie Piper — everyone who has ever been credited in the opening since the revival first began, with the exception of Christopher Eccleston and the addition of Sladen. Also back are Mickey, Jackie, Wilf, Harriet Jones (Former Prime Minister) and basically every recurring character in the revival, plus Gwen and Ianto from Torchwood and Luke, K9 and Mr Smith from The Sarah Jane Adventures. Whew!
- The alte Frau who met Martha at the castle; when the garrison fled, she took their duty upon herself, and further still came within an ace of shooting Martha dead to ensure the Osterhagen Key would not be used.
- Jackie takes a level in this too. Now she blows up Daleks.
- Sarah Jane and Rose come equipped with a BFG and exploding necklace.
- Rose has one of these.Rose: Hello boys! Do you like my gun?
- Jack's is pretty big too. Please - get your mind out of the gutter. We meant the gun, not anything else!
- Mickey and Jackie of all people even have BFGs. They're endemic.
- Rose has one of these.
- Big Damn Heroes: Mickey and Jackie saving Sarah Jane Smith from a pair of Daleks early on.
- Bilingual Bonus: The German dialogue. Translation available on the BBC website.
- Bittersweet Ending: Rose and the Doctor are finally reunited, but he has to watch her fall in the arms of another man (his clone no less!) and leave her behind forever. Donna saved not only the entire Earth (and the other 26 planets) but all of creation, but can't remember or else she'll burn up. So she has no idea how important she is, and the Doctor's on his own again. Sarah Jane points out to the Doctor that he has many friends who who love him, quite a few of whom remain on Earth, in the main universe, and with their memories intact. The Doctor then goes to travel alone.
- Break the Cutie: The Universe really hates Ten. Davros' Breaking Speech was bordering on Mind Rape, reminding the Doctor of all the people who have died for him and accusing him of creating soldiers out of his companions.
- Call Back:
- The Reality Bomb annihilates humans with the same effect as Bad Wolf/Rose annihilated Daleks with.
- The BFG that Jack uses is the old Defabricator he turned into a gun and used on one Dalek in "Parting of the Ways".
- A very small one: Sarah Jane and Rose are happy to see each other, having become friends back in "School Reunion".
- Calling the Old Woman Out: The Doctor lets Sylvia have it for her awful treatment of Donna.
- Cannot Spit It Out: The Doctor can't complete the sentence "Rose Tyler..." from "Doomsday" but Handy can. It's implied that Ten deliberately didn't spit it out to make sure Rose went with and accepted Handy.
- Chekhov's Boomerang: The show finally gets its last bit of mileage out of the Doctor's lost hand. It's now turned into a full sized copy of himself and so it absolutely cannot turn up again.
- Cloning Blues: Averted: the Other Doctor doesn't angst about how he isn't "real" and even calls himself "The Doctor" because he technically is. Although Rose initially does, and he has to convince her of the fact.
- Continuity Porn: So much, so much, so much!
- Flash Back to everyone who sacrificed themselves for the Doctor in the new series.
- Davros recognizing Sarah from "Genesis"
- The return to Bad Wolf Bay.
- A nod to "The Unquiet Dead"; Gwen is a spatial genetic multiplicity (read: identical relative) of Gwyneth.
- Doctor-Donna remembers how to fix the TARDIS' Chameleon circuit, like the Sixth incarnation. Since she has the Doctor's mind it's implied that he can fix the Tardis Chameleon circuit, he just doesn't want to as he likes the police-box shape.
- Doctor-Donna's fate is sealed as her mind has absorbed too much information to possibly contain. It's a very similar fate to Bad Wolf/Rose, though the solution is different.
- Sarah Jane was given the warp necklace thingy by a "Veran soothsayer"; the same one who gave her the puzzle box in The Sarah Jane Adventures's "Whatever Happened to Sarah Jane?"
- Luke mentions that "Maria and her dad" are safe "in Cornwall".
- Ten asks Rose what happened in the Alternate Universe since they run a few years ahead of the prime universe. He previously used this knowledge to save the Earth from man-made catastrophic volcanic eruptions many incarnations ago.
- Couch Gag: The previous episode's use of multiple names in the opening credits, with additional actors receiving credit over the first post-credits scene, is repeated. As of 2016, these two episodes are the only ones to do this.
- Crisis Crossover: Ianto, Jack and Gwen from Torchwood, Sarah Jane, Luke and Mr Smith from The Sarah Jane Adventures and Rose, Martha, Mickey and Harriet Jones and basically everyone connected to the show since RTD got hold of it all turn up. Even K9 gets to appear. Crisis of Infinite Doctors, perhaps?
- Demoted to Dragon: Davros. Despite being the original master of the Daleks and the Doctor's Arch-Enemy, it's made clear that the Supreme Dalek is the one who's calling the shots, and Davros is in fact his minion.
- Deus ex Machina:
- K9 being called out at exactly the moment he's needed. Good dog!
- The hand becoming another Doctor just in time to save the TARDIS, although technically that would be a Deus ex Manu. Also the Ood and Caan knew it was coming all along.
- Didn't See That Coming: Davros certainly didn't know that the Doctor had dumped regeneration energy into the hand. Only the Doctor clone and Donna knew that it had set the hand up to instantly grow a new Doctor through spontaneous metacrisis (he only knew after the fact, and only Donna knew when she was told). NOBODY knew that zapping Donna after all of that happened would trigger the Time Lord brain in Donna.
- Discontinuity Nod:
- There has never been a being that's half-human/half-Time Lord before. Never ever ever and the Doctor certainly isn't one.
- Davros being little more than a slave to the Daleks, and in fact being taken for a ride by Caan, could also be a similar nod to the post-Davros Dalek situation. Many fans lamented that after "Genesis", the Daleks had become nothing more than thugs for Davros himself, although this was rectified in "Revelation" and "Remembrance".
- Disney Death: The Doctor was mortally wounded in the last episode, and not only did he regenerate, he didn't have to change his apperance.
- Dragon-in-Chief: Inversion. The Doctor mocks Davros as the Daleks' "pet", and he is actually a prisoner, kept alive only to help them construct the Reality Bomb and will likely be exterminated once the plan is complete. He is not The Dragon in any meaningful sense, but nonetheless he is a minion serving as the de facto main antagonist.
- Earth Is the Center of the Universe: "Only one planet left! Oh, and guess which one." A literal example too, as the Medusa Cascade is at the centre of all creation.
- Earth-Shattering Kaboom: The Daleks prevent Martha Jones from using the Osterhagen Key doomsday device. Just as well.
- Easy Amnesia: Inverted. Donna's memory isn't wiped that easily, but anything that reminds her of her travels with the Doctor will restore it and kill her.
- Evil Sounds Deep: The Supreme Dalek has one of the deepest Dalek voices yet.
- Explosive Overclocking: Donna nearly suffers from a biological version of this, with her body unable to contain the Doctor's intellect.
- Fanservice: Naked Doctor clone.
- "Flowers for Algernon" Syndrome: Yet another trope that applies to Donna's metacrisis. A Time Lord's vast intelligence is killing her via overloading her human body so The Doctor erases her mind and returns her to her previous shrilly self.
- Foreshadowing: Dalek Caan's declaration of NO MORE!! after having plunged through the Time War would be revisited much later during the 50th Anniversary Special.
- Gambit Roulette: Dalek Caan's scheme to wipe out all the Daleks by creating a new Dalek empire has been in the works for ages. Being a prophet definitely helped.
- Go Mad from the Revelation: Dalek Caan is a downplayed version. He's a little wonky but he knows exactly what he is doing.
- Good All Along: Dalek Caan, who, while crossing through time lock and losing his mind, came to a Heel Realization, and decided to destroy Daleks. Although he mentions that even without his help, the good guys would have still won.
- Gratuitous German: "Exterminieren!"
- The Greatest Story Never Told: Donna saved all of reality, but can never know it, not ever, because then she'll die. However, the Ood will make sure that Doctor-Donna is never forgotten.
- Half-Human Hybrid: Doctor Clone and Doctor-Donna are a time lord/human and a human/time lord, respectively.
- Ham-to-Ham Combat: Possibly one of the most glorious examples in the series' history, with Doctor-Donna, Davros, the Daleks and the Doctor himself engage in epic hammy warfare.
- Heel Realization: Dalek Caan is essentially the first Dalek to realize that his race are evil bastards of his own free will, not involving genetic mumbo-jumbo. This after killing his former superior, Dalek Sec, for basically the same thing.Davros: (shocked) You betrayed the Daleks?
Dalek Caan: I saw the Daleks. What we have done throughout time and space. I saw the truth of us, creator, and I decreed: No more!
- Heroic Sacrifice: Davros savagely critizes the Doctor for turning his companions into people who do this and kill themselves on his behalf.
- Hybrid Power: The Doctor undergoes a "biological meta-crisis" in which he uses regeneration energy to form a clone which has some of Donna's personality. More importantly, the same process gives Donna the Doctor's mental prowess, which, combined with her "gut instinct" as a human, makes her a hypergenius capable of things even the Doctor would never think to do. Unfortunately, the human-Time Lord meta-crisis proves to be unstable, and would kill her if she didn't have her memory erased.
- Hypocrite: Davros has the gall to use his parting words to call The Doctor THE DESTROYER! OF! WORLDS! when he was about to wipe out every universe ever just minutes earlier.
- Ironic Echo: "I was going to be with you, forever."
- Just Following Orders: Martha is going to destroy the Earth. She says, "I'm a member of UNIT, and they gave me the Osterhagen Key. I've got to do my job. I'm sorry." Next scene, where is she? Near Nuremberg.
- Large Ham: Even discounting the usual suspects, Doctor-Donna and Davros could have stocked a deli section all by themselves. She has the high energy techno babble and he's got the evil gloating.
- Laser-Guided Amnesia: Played With. The Doctor can't just wipe Donna's memories of his consciousness; he has to wipe all of her memories of him and their travels together. If she ever remembers anything about him, she would end up remembering everything and would die.
- Left for Dead: Davros and Dalek Caan are last seen in the exploding Crucible. The Doctor offers to save Davros but he refuses.
- Lightning Can Do Anything: In this case, provide the jolt to activate the time lord mind inside Donna.
- Mad Oracle: Dalek Caan is an oracle and may be mad but he is much more in control of events than anyone expects.
- Mama Bear:
- Mess with Luke's life at your own peril; Sarah will go to any length - even killing - to save him.
- Don't lay a finger on Rose either: Jackie will hurt you.
- Mercy Kill: What the Osterhagen key is intended to do to Earth and humanity; blow them all up if their suffering becomes too great.
- Misunderstood Loner with a Heart of Gold: Dalek Caan. The good guys think he's both evil and crazy and the Daleks shun him as an abomination, but he helps save the universe in the end.
- Mix-and-Match Man: The Doctor + Donna clone.
- Mood Whiplash: This is averted in the final moments, with the Doctor still looking rather glum over Donna's Laser-Guided Amnesia. He pulls the lever on the TARDIS to leave, then the credits roll, and that's it. Unlike the last three series finales, the somber mood is not suddenly swept away by bizarre hijinks.
- My Friends... and Zoidberg: Everybody can help with the TARDIS... except Jackie. She should just stand over there... thanks.
- My Skull Runneth Over: Donna is burning up from all the information inside her head. Nine hundred years of time lord education and adventure is too much for a human mind.
- My God, What Have I Done?: The Doctor has this after he hears what happens to Harriet Jones (former Prime Minister), given that he deposed her.
- Mythology Gag: Even though in this phrase it is technically referring to the same incarnation of the Doctor, the line "Three doctors?" evokes the old crossover episodes.
- Naked on Arrival: The Doctor Clone is born naked, "oh yes".
- New Powers as the Plot Demands: The Doctor's ability to cancel a regeneration in progress by siphoning his energy into a receptacle is seen for the first time.
- Nice Job Fixing It, Villain: Had Davros not fired at Donna, his victory would have been assured because it activated the time lord mind inside her. It worked well on Doctor Clone so he figured it would work on her.
- No Endor Holocaust: Dragging the Earth at super-light speeds across half the Universe would cause more trouble than a mild earthquake. Just dragging it out of the moon's influence would cause endless disasters. Presumably the TARDIS extended its Inertial Dampening but even with the dampening, the same global earthquake that knocked potted plants off shelves in London probably set off massive avalanches and landslides in other regions.
- Not So Different: Davros tries to pull this one on The Doctor; he makes Daleks and the Doctor makes Companions. Both of them are soldiers.
- Nothing Can Stop Us Now!: Davros shouts this when the Reality Bomb is ready and all of his enemies are defeated.
- Obfuscating Insanity: Dalek Caan may well be completely crazy (the script never really says one way or the other), but he is also way, way more in control of events than anyone thinks it's possible for him to be until it's too late for Davros or the Daleks to stop him. This is the only reason the universe gets out alive.
- Omnicidal Maniac: "The DESTRUCTION! OF REALITY! ITSEEEELLLLLFFF!!!" Davros has been an Omnicidal Maniac for quite some time. Now that he's capable of destroying reality, he's overjoyed.
- Ooh, Me Accent's Slipping: The Doctor, of all people, in the scene at Bad Wolf Bay, as David Tennant lapses into a Scottish accent after three solid years of credible Estuary.
- Out-Gambitted: Both Sarah Jane and UNIT have gotten their hands on two devastating super-weapons, the Warpstar that will destroy the Dalek mother ship and the Osterhagen Key that will destroy the Earth (thus ruining the Dalek's plans), respectively; Sarah Jane allied with Mickey Smith and Jackie Tyler to infiltrate the ship and Martha Jones risked capture and death in Dalek-occupied Germany to be in position to activate the Key. Much of the episode focuses on the efforts of several characters to get in the right position to use them, and when the moment comes many of them contact the Daleks via video link to warn them to back off or die. It seems that the Daleks' Evil Plan is finished... except that Davros just transports everyone to his vault, capturing them and rendering both weapons useless. Then Donna and Doctor Clone show up with their Dalek-destroying weapon... only to get zapped and the weapon destroyed.
- The Power of Friendship: All of the Doctor's previous companions have shown that they're quite willing to die (in some cases, repeatedly) to protect him. This episode puts a dark twist on this with the claim by Davros that the Doctor basically turns everyone who loves him into living weapons for his cause.
- Promotion to Opening Titles: Same as the last episode, with Noel Clarke and Camille Coduri added post-titles.
- Prophecy Twist
- "That version of Donna is dead." "The end of everything (Dalek)".
- Threefold Man... and all this time people thought a previous Doctor was coming back.
- Same for Doctor-Donna, which about everyone assumed was the Ood being incapable of telling the two apart.
- "Most faithful companion". The TARDIS "died" (or was declared so); his human version went to Pete's World (when Rose did, she was considered "dead"); the Donna that travelled with the Doctor, who vanished along with Doctor-Donna. Which is, as the name says, partly the Doctor himself. .
- Punctuated! For! Emphasis!: "The DESTRUCTION! OF REALITY! ITSEEEELLLLLFFF!!!"
- Put on a Bus: Everyone bar the Doctor goes back to their pre-crisis lives; Torchwood, investigations, the alternate universe, UNIT, etc.
- Reset Button:
- The Doctor mind-wiping Donna.
- The Doctor blocking Jack's teleporter again.
- Averting this trope, The Doctor mentions that everyone else in the universe who knows what Donna did will remember.
- The Sarah Jane Adventures has confirmed that there was indeed no "Reset" and that the human race is now fully aware of the existence of aliens.
- Rule of Three:
- It only takes three Osterhagen Stations to activate the Osterhagen Key Fail-safe.
- We have three instances of the Tenth Doctor.
- The daleks are using 27=3^3 planets to power their reality bomb.
- Running Gag Stumbles: Played for Drama. The Tenth Doctor's previous series each ended with him bidding farewell to his companion and getting back to business in the TARDIS, only for an unexpected and comical cliffhanger to ensue. In this finale, however, he parts ways with Donna, somberly returns to the TARDIS, and then... episode's over.
- Self-Destruct Mechanism: The Earth has 26 strategically placed nukes that will tear it apart. This is Osterhagen.
- Shout-Out: Davros is basically Emperor Palpatine in a hover-chair. The melted face, the constant talk of fulfilling destiny, and he even shoots lightning! (However it should be noted that most of these elements date back to when Davros was introduced in 1975 — eight years before Palpatine was first seen on screen.)
- Significant Anagram: "Osterhagen", as in the Osterhagen Key, is an anagram of "Earth's Gone".
- Some Kind of Force Field: Trapping our heroes is containment zone that looks like a spotlight.
- Spoiler Opening: Averted. Noel Clarke and Camille Coduri's guest-star credits don't appear on screen until the characters make their surprise reappearance.
- Stunned Silence: The reaction of Donna, Rose and Captain Jack when the Doctor regenerates into... himself.
- Suicide by Cop: Dalek Caan's prophecies were just a ruse to create a situation where his entire race (and Davros) were completely exterminated as he had finally realized that the universe would be a much better place without them around.
- Take a Third Option: The Doctor "bailing out" of a regeneration by siphoning the energy off into his severed hand instead.
- The Doctor's method of resolving his relationship with Rose.
- Techno Babble: Doctor-Donna fires techno terms like a machine gun as she stops the Reality Bomb, frees everyone and then disables the Daleks.
- Tempting Fate: Davros: "AND NOTHING CAN STOP THE DETONATION! NOTHING! AND NO ONE!" Honestly, he was begging for it.
- "The Reason You Suck" Speech: Davros howls one at the Doctor in the moments before the Crucible self-destructs.Doctor: Davros! Come with me! I promise I can save you!'Davros: (berserk with fury) Never forget, Doctor...YOU DID THIS! (Gestures at the destruction around them) I name you forever; YOU are the Destroyer of Worlds!
- Took a Level in Badass:
- Gwen and Ianto taking on the Dalek with G36s.
- This entire episode goes out of its way to establish the position of ex-companion as a badass prestige class, even giving them a cool collective name as "The Children of Time".
- Donna had already taken a level in badass during her time with the Doctor, but she takes another level when she becomes imbued with his consciousness. Doctor-Donna is a glorious thing to see. Too bad it has to result in a Reset Button for her personality.
- Translation Convention: Averted with the German-speaking Daleks. The TARDIS's Universal Translator only works when the Doctor is present.
- True Companions: The "Children of Time" are all ex-companions and very good friends.
- Twin Threesome Fantasy: Three doctors?Jack: I can't tell you what I'm thinking right now.
- Two-Keyed Lock: It takes three Osterhagen Stations to activate the Osterhagen Key Fail-safe.
- Unwitting Pawn:
- Dalek Supreme does know better than to trust the wild prophecies of a madman and initially dismisses Caan. Davros, however, claims that Caan "only speaks the truth", and can't imagine that one of his creations would betray him. Again.
- Davros is outsmarted by his own creation in the most thorough way since the character's introduction.
- Victory-Guided Amnesia: After saving all of creation, Donna's memories are erased so she can continue to live.
- Wham Episode:
- Ten uses his regenerative energies to create the Meta-Crisis Doctor.
- Davros is seemingly killed again, not that anyone expects him to stay dead.
- Rose is convinced by the Meta-Crisis Doctor to spend her life with him.
- Donna's brain is wiped of ever knowing the Doctor. Due to the human brain not being big enough to store the knowledge of a Time Lord, if she somehow remembers him, she will die.
- What Happened to the Mouse?:
- Of the Doctor's companions on Earth at this time who have faced the Fell Saltshakers, we know that Sarah Jane, Rose, Jack and Martha survived and Donna too (minus her memories). What about the other 20th century Earth companions (many of whom were confirmed to be active as of the fourth series of The Sarah Jane Adventures) doing?
- We never exactly find what happened on the other planets the Daleks stole. However a comic-strip later that year, The Forgotten, gives some information about what happened on one of the worlds.
- Where's the Kaboom?: The Doctor and his companions helplessly watch in horror while Davros laughs in glee as the reality bomb painstakingly ticks down to 1. Then... nothing happens.
- Jack, Rose and Donna's "huh?" after the Doctor apparently cancels out his regeneration counts, especially for Rose as she's seen it happen before.
- You Are Not Alone: Sarah Jane reminds the Doctor:Sarah Jane: You know, you act like such a lonely man, but look at you! You've got the biggest family on Earth!
- "DETONATE! THE REALITY! BOMB!"