The one where the Doctor goes too far.
Written by Russell T. Davies and Phil Ford.
The Doctor steps out onto the surface of Mars, wearing a very familiar space suit. He's come to Mars on a whim, and quickly finds himself looking upon a human colony called Bowie Base One (looks like there really is life on Mars). He's captured right away, though, by a little robot called Gadget and taken to see the person in charge of the base: Captain Adelaide Brooke.
The Doctor thinks that the cutesy robot is rubbish (although robot dogs are cool, of course), but otherwise loves the base. It doesn't take long for the Doctor to realise exactly where he is, and when: November 21st, 2059. Captain Brooke and her crew are the first human colony on Mars. The Doctor is a huge fan of their trip, and as he rambles through their history while madly squeeing, we see flashbacks to a series of articles with obituaries. The crew will die here today. The Doctor knows it and knows that he shouldn't interfere, because this is a tremendously important fixed point in time. He'll never know what kind of monster attacked them, but that's fine, and he'll just leave now.
People go missing. One by the name of Andy is already dead. Another, Maggie, is found conked on the head and taken off to the medical dome. The Doctor should leave now. But he lets himself be roped into the investigation by Adelaide, into the bio-dome, joined by Expendable Crewman Tarak. Within a good few minutes, Tarak is separated from the Doctor and finds what appears to be Andy... water flowing off of Andy like he's a theme park ride. Andy's face is distorted, cracked and gushing water.
The Doctor keeps making vague excuses about how he has to go.
Maggie, deep in an isolation room, also shows signs of... whatever this is. She's freaking out the base's nurse, Yuri. He contacts Adelaide, and she realises it's best to leave the dark, scary giant building with lots of places for something to jump out at them. But they make one last look around for Tarak... and find him in the same water-zombie state as Andy, who is standing right next to him, or what used to be him. Dragging Adelaide away, the Doctor announces it's time to run, and they barely escape the two infected humans.
They lock the two infected forms out of the main central dome. These water creatures, Maggie included, are demanding to go to Earth where they can thrive in water. The Doctor raises up the question of who else is infected, if the virus/parasite/whatever isn't inside everyone else on the base already, as it thrives in the water and obviously came from the Martian water that everyone has been drinking. Adelaide goes off to check the ice cap on top of which the base is built, while the rest of the crew begin prepping for escape to Earth. The Doctor knows that he should be leaving, but he decides to run off and join Adelaide instead, seeing as he can't leave without his spacesuit.
At the ice cap water extraction dome, the Doctor and Adelaide look out over a rather impressive ice cap while the Doctor rambles about some old enemies of his the Ice Warriors. Adelaide begins to question the Doctor about why he's so eager to leave and how he knows so much about the Mars colony. The Doctor explains that this is a "fixed point in time", confusing the hell out of Adelaide for a few moments before the Doctor quickly changes the subject to why Adelaide came out into space: The Dalek Invasion of 2009* . She looked into the eyestalk of a Dalek, it looked right back, and left her to live. Adelaide simply wished to follow that Dalek out again not to kill it, but to meet other creatures in peace.
The Doctor rambles on about how awesome Adelaide's descendants will be, all inspired by her heroic journey to Mars, and how massively important they'll all be to the future of all time and space. More newspaper flashbacks. It freaks the hell out of Adelaide in general. In seconds, it's revealed that everyone else still alive doesn't have the virus so it's time to start leaving!
...or it would be, if the infected bodies that were once Andy and Tarek didn't climb up on top of the central command building to start spewing water everywhere.
The Doctor, now with space suit, finally starts to leave... but Adelaide refuses to open up the airlock hatch until the Doctor explains why he's being so awkward around everyone. He explains it all for us (and Adelaide): this very day is the day that Bowie Base One is destroyed with all hands lost. Adelaide's heroic death is what will inspire her descendants and what will propel humanity into interstellar travel. It has to happen.
The Doctor leaves solemnly, listening through his helmet to the attempts of the remaining crew to fight fate the best they can. He hears about the water seeping into the main control room, taking out another member of the crew. Yet another is infected as a single drop hits his face and this one demands the crew leave him before he's infected. The pilot of the shuttle, Ed, is also infected but chooses to blow up the shuttle rather than let the Earth get infected. The resulting explosion traps our remaining three crew-members in a single storage room, and knocks the Doctor quite a good distance.
All looks grim for Adelaide, Yuri and Mia... until the Doctor walks into the storage room, shouting out orders like a maniac and trying to save those people he'd declared dead. Adelaide begins to panic, wondering why the Doctor is throwing his previous worries out the window. Almost foaming at the mouth, the Doctor launches into a speech about how there are laws of time, but he can warp them. He's safe, he knows it's not his time yet, because he'll be killed when someone knocks four times. So today, he's decided that as many people as people are going to be safe too! The laws of time that were once enforced by a group of people a group long since dead:
Adelaide believes that the Doctor's gone insane. Gee, whatever gave her that idea? The Doctor declares he's also fighting time itself. Not even close to giving up, the Doctor finds that robot buddy Gadget in storage and uses it to bring the TARDIS to him even while Adelaide sets the base to self-destruct. With four seconds to go, the TARDIS begins to rematerialise. As it finishes, the countdown reaches zero, the base blows up and the TARDIS whisks everyone away.
The Doctor takes the survivors to Earth: same time, same day. Mia, unlike many companions of the past, utterly freaks out at the TARDIS itself and flees Yuri running after her. The Doctor himself is all grins and smiles, proudly proclaiming how time now obeys him. In recognition of his new exalted status, he gives himself the new title of Time Lord Victorious. Not only did he save two of the "little people", but he also saved one of the "big ones".
Adelaide does not take this well, trying to reason with the Doctor claiming that no one person should have so much power. However, she just cannot get through to him, as the Doctor is finally realising everything that he can do, all that he can accomplish. He can warp time, escape death, open up the door to Adelaide's home.
Adelaide simply glares at the Doctor and enters her own home. A blue flash through her windows makes it perfectly clear just how the Doctor's hubris will be repayed.
Thoughts flash through the Doctor's head of reading about Adelaide's once noble death, and that of the two crew members who originally didn't make it. They begin to change, and his face gleams with horror. His fond memories of Bowie Base One's sacrifice have been rewritten... for the worse. The Doctor breaks, realising that he's gone too far. Ood Sigma appears for a moment, and the Doctor questions him, wondering if this is when he's supposed to die.
Ood Sigma simply vanishes, leaving a distressed and panicked Doctor to dash into the TARDIS and lock the door behind him. The Cloister Bell begins to go off, but the Doctor declares "no" and valiantly throws himself into his final episode.
- 20 Minutes into the Future: The home time period of Adelaide and her subordinate crew and family. Born in the late 1990s, her 60-year-old self (as seen throughout most of the special) lives during the 2050s.
- Abandon Ship: The crew makes a hasty attempt to bug out, but Maggie gets in the shuttle and infects Ed before he can lock her out. So he sets the Self-Destruct Mechanism before the infection takes, blowing up the shuttle.
- The Aesthetics of Technology: Although the Doctor is using a spacesuit from humanity's future, it doesn't look like it, making the comment on its advanced technology a bit odd. Presumably this is because it's more lightweight and noticeably less bulky than the suits they're using, which may be why they wonder where it came from.
- Badass Normal: Captain Adelaide is just a normal human, which makes how she endures the events of the episode stand-out more.
- Be Careful What You Wish For: Though The Doctor does start to go mad over helping her and the other survivors, it was Captain Adelaide who begged for him to intervene and save her and the others in the first place, before she has a sudden case of buyers remorse.
- Belligerent Sexual Tension: It's heavily implied that something may have gone on between Adelaide and Ed that ended very badly, hence why their relationship is extremely tense.
- Big Damn Heroes: The Doctor's return to save Captain Adelaide, Yuri and Mia from the Flood, whether the Captain wants it anymore or not, complete with dramatic lighting and music.
- Body Horror: The people infected by the Flood become water-bloated, ruptured-skin-sporting, dead-eye-having monstrosities.
- Bold Explorer: Captain Adelaide's the commanding officer of humanity's first permanent Mars colony. Her granddaughter also looks forward to following in the footsteps of the trope and become a space explorer as well.
- Borrowed Catchphrase: The Doctor in the midst of his HeelFace Turn uses the Master's "You will obey me", but applies it to the laws of time.
- Break the Haughty: Adelaide does this to the Doctor after his behaviour horrifies her and disgusts her. And what she does leads to a massive Tear Jerker, though one that helps the Doctor snap out of his creepy delusions of grandeur.
- Brick Joke: "You were right, Doctor: bikes."
- Burning Rubber: Gadget leaves flaming tracks after the Doctor soups it up.
- To "The Fires of Pompeii", the last time fixed points in time were mentioned. He also used the TARDIS to save a couple of people at the last minute in that episode, although this time it is not shown as a good thing. He rehashes the argument he had with Donna Noble in that episode, then says everything he does to try to help just makes it happen, when trying to convince Adelaide to let him leave.
- The Doctor is wearing the spacesuit from Sanctuary Base 6, as seen in "The Impossible Planet".
- When the shuttle explodes, several of the Doctor's lines about the Time Lords from the last several seasons are repeated as he stares at the wreckage.
- The Captain: Adelaide is very much in charge of her base and ship.
- Chekhov's Gun: Gadget the robot gets used as a high-speed Segway by the Doctor and Adelaide to escape the infected crew members, and later is used to bring the TARDIS to the Doctor and remaining crew on the ship.
- Chronic Hero Syndrome: Really gets to the Doctor in this episode. The Bowie Base One disaster is a fixed event, and as such he would've been more rational and just left right away, but Adelaide forces him to get just involved enough to let his heroic instinct get to him.
- Complaining About Rescues They Don't Like: Captain Adelaide tearfully begs the Doctor to break the rules and intervene and save her and the others, and when he finally does she suddenly has nothing but complaints about it and him when they get back to Earth.
- The Conscience: Adelaide acts like this to the Doctor, especially in the last scene, where she calls him out for breaking his principles and playing around with historical outcomes and the fates of individuals as if he had the right to do so. Captain Brooke might be icy and strict to him, but she's open to admiring him, as long as he keeps to his ethics and doesn't succumb to delusions of A God Am I.
- Conscience Makes You Go Back: The Doctor is unable to resist Adelaide's pleading for him to save her and her crew, especially listening in as the Flood murders them one by one, and breaks the rules in an attempt to do so.
- Continuity Nod: Given that they have a good 45 years to work with, this is to be expected...
- The Doctor mentions the Ice Warriors, and the humans regard the idea of a sentient race once living on Mars with skepticism.
- This isn't the first time this Doctor has met a "funny robot"... Is it at all possible that was a slam against Kamelion?
- The Philippines is strongly implied to be a world power by this point. Those who recall a certain Fourth Doctor serial should know that it will get much more powerful in the future.
- Cool Old Lady: Adelaide is of the Reasonable Authority Figure mould. While she gets to know the Tenth Doctor only for a short time, he fails to intimidate her even when he goes off on his unnerving Motive Rant about enjoying the thought of becoming the Time Lord Victorious.
- Creator Provincialism: Subverted, for once; though there seem to be a disproportionate number of Britons around (and the base is named after a British musician), there is a realistic international representation, including the major space powers of the United States and Russia. Many countries that are currently not too important on the world stage are described as being major powers after an "oil apocalypse" which is never really explained (it only gets a brief mention from Adelaide in which she describes that the human race was almost wiped out). Two of these are Spain and the Philippines.
- Danger Takes a Backseat: How Ed and the shuttle are lost; Maggie slips in behind him.
- Do Not Go Gentle: The Doctor refuses to let these people, little or otherwise, die without a fight.
- Dug Too Deep: There was something living in the ice that The Team dug up for drinking water.
- Dwindling Party: Captain Brooke's crew succumbs to the virus until only three are left.
- Eldritch Abomination: Via parasites in the Martian water that turn people into craggy, water-spewing zombies with unholy screams that can free the real Eldritch Abomination hiding deep within the ice.
- Even Evil Has Standards: Daleks will literally kill everything and anything in existence that is different to them if they can; however, messing with a fixed-point in time is something that not even they will do and thus a Dalek actually spares a young child Adelaide when it comes across her.
- Exty Years from Now: The story takes place on 21 November 2059. RTD gambled on the episode airing on 21 November 2009 and lost, but it's close enough.
- FaceHeel Turn: The Doctor's shift in morality almost turns him into the Master Mk. II.
- Face-Revealing Turn: The background music swells as Tarek approaches the now-infected Andy and he turns his face to the camera.
- Famous-Named Foreigner: Yuri Kerenski brings to mind Alexander Kerensky, the last leader of the Russian Duma before the October Revolution.
- During his A God Am I stage, the Doctor starts acting like the Time Lords who appear two episodes later (same Screw the Rules, I Make Them! personality). He also uses some of the Master's quotes. Guess who also shows up in the next episode?
- When Adelaide heads into her house we see her draw her pistol. Had the Doctor been paying attention to her instead of ranting to himself, he might have stopped her from killing herself. Then again, if he had been paying attention to her at all he would have realised how distraught she was and possibly got the idea that going A God Am I on her was a bad idea.
- Forgot I Could Change the Rules: Playing with a Trope. At first the Doctor is all "I shouldn't be here; I should leave" because he can't change the rules. Then he decides that, as the last of the Time Lords, yes, he can change the rules. So he meddles and then he realizes that while he can change the rules if he wants, it will cause seven kinds of hell to break loose. Upon this realization, he states "I've gone too far."The Doctor: The laws of time are mine! And they will obey me!
- For Want of a Nail: Everything could have been avoided by filtering the water. In fact, they were filtering the water, but it turns out the spares they brought along didn't fit, and one of the filters failed just before this all started.
- Freeze-Frame Bonus: The Doctor makes a big deal out of the fact that Mia is "only 27 years old." However, if you look at all the articles shown about the other members of the crew, Yuri is also 27 and Roman is 25. For Roman's, it's pointed out in the article that he is the youngest member of the crew.
- Friendly Enemy: The Doctor and Adelaide act mildly antagonistically to each other, but this is purely down to her not entirely trusting his approach and ideas and the Doctor not being too keen on her paying close attention to his methods.
- Glass-Shattering Sound: The zombies' roars cause the glacier to crack.
- A God Am I: The Doctor starts thinking of himself as the Time Lord Victorious and talking in such a way that suggests he thinks all of time and space is going to bend to his will. For those who didn't get the point, bear in mind that the Doctor's comment about how the laws of Time will obey him is eerily similar to the Master's old Catchphrase of "I am the Master, and you will obey me!"
- Go Mad from the Revelation:
- A subtle execution of the trope but it certainly applies when the Doctor realises he changed nothing at all in the long run, in spite of his efforts.
- Despite what the entry below says, maybe Adelaide Brooke wasn't a Heroic Sacrifice at all; maybe she just freaked out at the thought of a sappy eccentric guy playing God and saving peoples' lives based on simply whether they are important or not.
- Humanoid Abomination: The infection in the water turns anyone afflicted by it into humanoid, dead-eyed water fountains functioning as nothing more than a Living Bodysuit for some ancient horror buried under the ice.
- Heroic Sacrifice:
- In the original timeline, Adelaide Brooke detonates the Mars base to save Earth from the Flood. In the altered timeline, she kills herself in an attempt to keep history on track, to save Earth from the Time Lord Victorious, or both.
- Ed detonates the rocket to stop the Flood from reaching Earth when he realises that it's on board and has infected him.
- Heroic Suicide: In the end, Adelaide does it as a defiant gesture of resistance against the Doctor's increasingly deranged toying with the idea of shedding responsibilities and changing history in whatever way it pleases him. Her suicide acts as proving a point that he can't just rewrite certain events as it suits him, even if it would result in averting the deaths of others. Though she is something of a hypocrite for having begged for his intervention in the first place, and suddenly being displeased with the consequences when he complies.
- Hypocritical Humour: "I don't like funny robots." As well as "Oh, well robot dogs are different!"
- In Spite of a Nail: In-Universe example: Adelaide commits suicide on Earth rather than dying on Mars, but not much of humanity's future is changed.
- It Can Think: Those infected by the contaminated water are not stupid, they even managed to short out the systems of an airlock to bust it open.
- Invincible Boogeymen: While Flood hosts can be slowed down, nothing in the long run can stop them - as the Doctor puts it, "water always wins". One by one the crew of "Bowie Base One" on Mars become infected, as only one drop of water is all that takes to convert someone.
- Irony: After all the complaining about being saluted, the Doctor salutes Captain Brooke.
- Jerkass Has a Point: Despite how unhinged the Doctor becomes over breaking the rules, Captain Adelaide DID beg for his intervention, and doing so does save her, Yuri and Mia by the end of the episode, where before in the original timeline everyone at the base died. Even after her suicide, Yuri and Mia are still alive thanks to him.
- Jumping Off the Slippery Slope: The Doctor begins to do this at the end, with a truly terrifying Motive Rant.The Doctor: There are laws, laws of time. And once upon a time there were people in charge of those laws, but they died!. All of them died! And do you know who that leaves? ME! It's taken all these years to realise it, but the laws of time are mine and they will OBEY ME!
- Kill 'Em All: Everyone human in the base will die; it's a Fixed Point in Time and thus a Foregone Conclusion. Except this trope is defied when the Doctor saves three of them! Yes, Adelaide kills herself, but Yuri and Mia are still alive at the end.
- Kirk Summation: Adelaide gives a brief but effective one to the Doctor after he interferes in events that could radically alter the future of the Earth and her own family.Adelaide: But... Susie... my granddaughter... wasn't she supposed to become... we'll never exist now.
The Doctor: Nah, Captain Adelaide can inspire her face-to-face. Different details, but the story's the same.
Adelaide: You can't know that! And if my family changes... the whole of history could change! The future of the human race! No one should have that much power!
The Doctor: Tough.
Adelaide: [backs away from the Doctor, unsure of what is going on] You should have left us there.
The Doctor: Adelaide, I've done this sort of thing before. In small ways, saved some little people. But never someone as important as you. [does an insane grin] Ooh, I'm good!
Adelaide: [shocked] Little people? What, like Mia and Yuri? Who decides they're so unimportant? You?!
The Doctor: For a long time now, I thought I was just a survivor, but I'm not. I'm the winner. That's who I am. A Time Lord Victorious.
Adelaide: And there's no one to stop you?
The Doctor: No.
Adelaide: [noticeably angry] This is wrong, Doctor! I don't care who you are! The Time Lord Victorious is wrong!
The Doctor: That's for me to decide.
- Knight Templar: The Doctor declares that he is the master of Time and he can do whatever he wants to make history go the way he wants so he can save whoever he wants. You don't like it? "Tough."
- Large Ham: The Doctor gets into a loud and erratic fit of heroics at the episode's climax.
- Little "No": The last line of the episode, from the Doctor, in response to the Cloister Bell ringing as a result of both his recent actions and events yet to come. He's not ready to die yet.
- Making a Splash: The unidentified parasites live in water and can generate water and shoot it at high pressure.
- Meaningful Background Event:
- Andy bites a carrot, then the shot changes to focus on Maggie. He remains out-of-focus in the background, convulsing and suddenly falling still.
- Same thing happens to Maggie later, with Yuri in the foreground.
- Meaningful Echo: It's pretty clear how far off the deep end the Doctor's gone when he starts echoing the Master's Catchphrase from the classic series.The Doctor: And they will obey me!
- Morality Adjustment: The Doctor briefly becomes a Knight Templar, declaring that he can do whatever he wants with the Laws of Time in name of saving whoever he wants. Adelaide straight up calls him a power-mad despot.
- Muggles: A Defied Trope on Adelaide's part. She objects to the Doctor's not-so-subtle insinuations that he rescued her from death for being "more historically important" than any of her crew members, just because she holds a higher rank than them and is more publicly famous in her own time.
- Multinational Team: The astronauts on the base. Several British and American, a German, a Russian, a Pakistani and an Australian and whatever Mia was; Freeze-Frame Bonus told us she was Korean-American (there's a South Korean flag sticker on one wall and her obituary said she was born in Houston and studied in Stanford), but Gemma Chan doesn't put on an American accent (and possibly didn't know she needed to. The obituaries were likely made during post-production; it's possible that they made the decision to have Mia be from Texas long after filming).
- Murder Water: Water which turns you into a bloated malevolent water-spewing being seconds after coming in contact with a single drop.
- My God, What Have I Done?: Going hand-in-hand with Go Mad from the Revelation, when the Doctor realises he let his arrogance go to his head."I've gone too far."
- Name of Cain: Maggie's full name is shown in the personnel files to be Margaret Cain. Not only is she one of the first people to be infected, but she appears to act as the ringleader of the infected crewmembers.
- Never Found the Body: No trace of either of Adelaide's parents was ever found. Which, considering they disappeared during the Battle of the Medusa Cascade, would seem to indicate that they ended up becoming victims of the Reality Bomb test.
- Nice Job Breaking It, Hero!: Several violators here. The TARDIS for bringing the Doctor to a fixed point, the Doctor for not leaving at the first opportunity, and Adelaide for not letting him leave immediately.
- Never Trust a Trailer: One of the trailers shows the Doctor mentioning the prophecy from the previous special ("he will knock four times"), just before some knocking starts. In the actual episode, it's only one of the water creatures and it only knocks three times.The Doctor: And three knocks is all you're getting!
- "No. Just... No" Reaction: Mia does not take well to the TARDIS's Alien Geometries on top of everything else that has happened this day.
- Noodle Incident: Some incident to inspire animosity between Adelaide and her number two is alluded to but never elaborated on.Ed Gold: [last words before sacrificing his life after being infected] Hated it, Adelaide! This bloody job. You never gave me a chance... you never could forgive me.
- No OSHA Compliance:
- Whoever decided that a room that was meant to quarantine people should have a basic seal and not a Hardinger Seal clearly didn't understand why an unbreakable seal would help to keep something contained.
- Whoever built the water system recognized the risk of water contamination and included filtration, but they packed the wrong filters for the water system.
- Not So Different: Many an Ironic Echo abounds when the Doctor starts to snap and unknowingly begins to channel the Master.
- Nothing Is Scarier: It is never revealed where the Flood came from, with available evidence making it equally likely that the virus was natural or some artificial creation made by the ancient Ice Warriors, particularly since a host responded to the Doctor talking to it in Ancient Martian.
- Oh, Crap!:
- There are several moments of this throughout the story, considering only one drop of water can infect someone.
- The biggest one is at the end, though: the Doctor, on his way back to the TARDIS, loses it when he realises Adelaide has killed herself, and it dawns on him what he just tried to do.
- One last one when the Cloister Bell goes off.
- Omniscient Morality License: The Doctor becomes so overwrought with the guilt and fear that everyone is supposed to die in the expedition that he snaps and saves the three remaining members whom he himself categorises as two "little people" plus one "big person". He declares himself "Time Lord Victorious", and says there's nothing anyone can do to stop him. Then Adelaide, who is quite frankly disgusted with this notion, does stop him by committing suicide, ensuring that her descendants lead the human race outside the cosmos, and the timeline is somewhat fixed. It took this for the Doctor to realize that his hubris had completely got the better of him.
- OOC Is Serious Business:
- Adelaide paying someone a compliment is noted to be a bad sign.
- The Doctor going Time Lord Victorious is awesome, and scary. Also, his solution to the problem is to use the TARDIS, something he almost never does.
- The fact that a Dalek decided to spare Adelaide shows how important not messing with fixed points in time is.
- Our Zombies Are Different: The Flood turns humans into water zombies. They've got the blank stare and the infected status, but absolutely no zombie gait. They're faster than you are.
- Out-of-Character Moment: During the final scene, the Tenth Doctor shows a very selfish side unlike his usual compassionate attitude. He argues with Adelaide that he gets to decide who's important and who's not, who gets to live and die, and calls himself a winner in a tone similar to how the famous Charlie Sheen calls himself a winner. When Adelaide calls him out saying he's wrong, he simply replies, "That's for me to decide." This is portrayed as what the Doctor is like if he's both wracked with guilt and loneliness for a long time and left without a companion to regulate him. By the end he's given a sharp wake up call about just how OOC he's being and it's the start of him realizing that he needs to regenerate because he's becoming dangerously prideful from being 10 for so long. Made even more alarming when you realize that, at the time of his regeneration, 10 lived less than a decade. As the Eleventh Doctor would later put it, he had "vanity issues" which caused him an abnormal amount of attachment to a specific incarnation and fear of regenerating.
- Pokémon Speak: Gadget Gadget!
- Pre-Asskicking One-Liner: "I don't hear anyone knocking!" *... knock... knock... knock* "Three knocks is all you're getting!"
- Real Life Writes the Plot. When the bio-dome scenes were being shot, the film lights woke up the birds, and a line was added to the script to explain the birdsong.
- Red Herring: After seeing that Maggie's eye colour did not change with the rest of her, the Doctor briefly theorises that she may have retained some of her humanity. However, the opposite turns out to be true, as she actually becomes the nearest thing that the story has to an individual Big Bad.
- Ripple Effect-Proof Memory: Yes and no; the Doctor's memories of history change at the end, but he seems to be aware that they've changed, and from what.
- Robot Buddy: Gadget was made from a drone, and his handler Roman is fond of him.
- Running Gag:
- The Doctor's insistence that they should have brought bikes. It's a Lampshade Hanging on the amount of running that goes on in this show.
- The Doctor commenting that he really should go.
- Sanity Slippage: The Doctor isn't accurately described as "sane" on his better days, but the effects of travelling alone for too long, coupled with hearing the cries of the dying astronauts over the radio, drive him into an incredibly disturbing moment of arrogance.
- Screw the Rules, I'm Doing What's Right!: With the crew screaming, panicking, and on the verge of death, how could the Doctor not help them, regardless of the Laws of Time?
- Screw the Rules, I Make Them!: Laws of Time? The only such laws are those that Time Lord Victorious decrees! ...Keep in mind that he believes this only because he's the last of the Time Lords.
- Sealed Evil in a Can: Humans accidentally released Sealed Evil in a Glacier when they tap it for water.
- Self-Deprecation: Again, the Doctor "doesn't like funny robots". He avoids self-deprecation later on by saying that robot dogs are different, making it closer to Hypocritical Humour.
- The first human base on Mars is called Bowie Base One. There's a David Bowie song called "Life on Mars".
- It's the wrong song, but the line "Planet Earth is blue, and there's nothing I can do" from "Space Oddity" seem significantly reflected in this episode (not to mention the event of someone dying in space for reasons never known back on Earth).
- When the Doctor changes history, we see news entries with changing text. Not to mention the flaming tire tracks.
- The sound the computer makes when it tracks the crew members is from 2001: A Space Odyssey.
- The horrific alien zombie virus is called the Flood.
- A member of the crew is infected by the virus when a drop of the tainted liquid hits their eye.
- The door that leads into the comm room where Adelaide contacts the Doctor closes with the same sound effect as the doors in the video game Doom. Fitting, given that the story revolves being possessed by supernatural forces in a creepy facility on Mars.
- The idea of one drop of water contaminating the global water supply may have been borrowed from Kurt Vonnegut's Cat's Cradle, in which a similar plot device causes the world's entire water supply to turn into ice-nine, bringing about a planetary Apocalypse How that is implied to cause the eventual extinction of all life on Earth.
- An Eldritch Abomination that takes the form of a watery liquid that turns people into zombies who want to bring about The End of the World as We Know It sounds a lot like the modus operandi of the title monster from John Carpenter's Prince of Darkness.
- A man shocking his male lover by buying him a car as a surprise birthday present, now where have we seen that before?
- Shut Up, Hannibal!: The Doctor delivers one of these to the infected Andy Stone who is banging on the door in a deliberate attempt to taunt the Doctor regarding the "four knocks" meaning his death.The Doctor: No, 'cos someone told me just recently, they said I was going to die. They said, "he will knock four times", and I think I know what that means, and it doesn't mean right here, right now, 'cos I dont hear anyone knocking, do you? [The Flood-possessed Andy, in response, knocks three times on the door in response]
The Doctor: Three knocks is all you're getting! [he electrifies the door; Andy is blasted back, screaming in pain] Water and electricity: bad mix!
- Silent Antagonist: The Flood only says a few brief lines very early on. From then on, the victims don't say a word.
- Slasher Smile: The Doctor briefly adopts one while using Gadget to remotely pilot the TARDIS.
- Survival Mantra: After the Doctor snaps, channels the Master and starts fighting the water: "Not beaten, not beaten."
- Tempting Fate:
- The Doctor when he realises where he is.The Doctor: I should go. I really... should go.
[hears a roar over the Tannoy]
The Doctor: Oh, I really should go...
- Later when they are evacuating the base.The Doctor: Right, I should leave! Finally! I should leave! Yuri my old mate, no, no point in me seeing the icefield? No point at all! No... [begins to run after her] ADELAIDE!
- The Doctor when he realises where he is.
- They Call Me MISTER Tibbs!: The Captain, upon being called "boss".
- Ungrateful Bastard: Captain Adelaide has shades of this after tearfully begging the Doctor to intervene, break the rules of time and save her and her crew. When he gives in, returns to save her, Yuri and Mia, only then does she suddenly worry about the timeline, regret it and throw away the Doctor's efforts to save her.
- Unwitting Instigator of Doom: Both the Doctor and Adelaide. Adelaide because she prevents the Doctor from leaving immediately (thinking him a spy), and the Doctor because he doesn't know the incident in detail.
- The Virus: The Flood can turn you into a zombie with just one drop.
- Water Source Tampering: Turned Up to Eleven with the aliens in the water and spreading via contamination of the base's supply.
- Well-Intentioned Extremist: The Doctor, out of a desire to save people, becomes mad with power and tries to alter the entire course of human history.
- What the Hell, Hero?: The Doctor himself is called out on this by Adelaide, most prominently at the ending where she tells him that "no one should have that much power".
- "World of Cardboard" Speech: The whole of the episode, the Doctor struggles with the taboo of changing Fixed Points in history, how his attempts to save them might doom then instead, and how he's only one Time Lord because the others are all gone. Then he realizes that, as the last Time Lord, he is Time Lord Victorious, so if he wants to save these people then he's going to and no one's going to stop him!
- The X of Y: "The Waters of Mars".
- You Can't Fight Fate: Fixed Points are fixed. You can't change them without screwing with history. Not even the last surviving Time Lord can say Screw Destiny.
- You Will Be Spared: The reason Adelaide is there at all is because a Dalek, presumably aware of her significance to history, elected not to kill her in 2009.
- Zombie Infectee:
- The first one gets inside the base by hiding her game face until she's in quarantine.
- Averted the second infectee immediately tells the others to leave him behind.