The one with the wibbly lever and us seeing double.
The episode opens up in the TARDIS, where the Doctor is busy working away at the console, when Amy comes to speak to him. When it's a choice between conversation and fixing his motor, the Doctor decides the latter is preferable and brushes Amy off. Not to be deterred, Amy continues to pester the poor Time Lord, saying she just needs to ask him something important. He promptly begins to call for Rory.
Feeling frustrated, Amy is surprised to see Rory is right there — underneath the console, fixing it along with the Doctor. A little miffed about being left out, she asks why he gets to help out. Rory points out that Amy is rubbish with machines: she can't even drive a car. (Point in fact, she can drive the car as long as there are no unexpected houses to crash into).
"You're just jealous because I passed my test first time," Amy says smugly.
"You cheated," Rory asserts. How? She wore a short skirt. "Have you ever seen Amy drive, Doctor? Neither did her driving examiner."
Suddenly, the ship is jolted and turns dark. When Rory was distracted by Amy's skirt through the glass floor above him, he accidentally dropped a thermo-coupling, which the Doctor specifically asked him not to do. Thankfully, everything should be fine. There was an emergency materialisation, so the ship should have safely landed wherever there was room —
Like inside itself.
Sitting proudly in the center of the TARDIS is a blue police box.
Rather unnerved, the Doctor goes to investigate the police box. He cautiously disappears through its doors — only to re-appear through the inside of their TARDIS doors. He spends a few moments playing with the rather Escher-like dimensional paradox, which Rory admits is pretty cool. Good thing too, because they'll need something to entertain themselves now that they're trapped for all eternity in an infinite loop. Because now, nothing can ever enter or leave this ship again.
Cue a second Amy walking in through the ship's doors.
Turns out that the police box has now drifted in time, so by going through it you can appear a few seconds in the past. This second Amy has come from the future because the Doctor just told — or will tell — her to go back and explain what's happened. Amy doesn't really understand, and future-Amy says she still doesn't; she's just repeating what she remembered her future self said.
In fact, everything she says has to be like she remembers, in order to keep the timeline stable. As such, the Doctor asks when present-Amy goes into the box, which she says will be right after she slaps Rory. Rory is not particularly happy with the idea of being slapped without having done anything, but after he seems a little bit too pleased by there being two copies of his wife around, present-Amy slaps him for that. So into the box she goes.
Not before she gets to flirt with herself first, of course.
Finally Present-Amy leaves, making Future-Amy Present-Amy. Which is all well and good, except they're still trapped...
And then Amy and Rory come running into the console room.
Once again, they came because the Doctor told — will tell — them to get into the police box. More confusion and flirting commences, the Doctor presses our present pair of companions into the blue box, leaving us with the normal set of companions. So, what now?
Well, the Doctor can get them out of this incredibly confusing loop, but only if he uses the right lever. If he uses the wrong one, the TARDIS will implode and they'll all die. "You don't know which lever," says Amy, disbelieving.
"No. But I'm about to find out."
And then another Doctor runs into the ship. "The wibbly lever!"
"The wibbly lever!"
He pulls the wibbly lever, and runs into the police box, just as it begins to dematerialize. Finally, it disappears, freed of its own infinite regression of time and space. There's no danger of accidentally dying, or blowing a hole in all causality. "But just in case: Pond, put some trousers on."
Go to YouTube for some clarity.
- All Men Are Perverts: The episode has a lot of fun with this. Even the Doctor can be seen checking out "The Legs" for a brief moment the first time Amy's skirt comes up in the conversation.
- Brick Joke: In "Space" there's the conversation about Amy getting her driving licence without driving at all, because the examiner liked the skirt. Then, when Amy flirts with herself in "Time":Present!Amy: Do I really look like that?
Future!Amy: Yeah! Yeah, you do.
Present!Amy: I'd give you a driving licence.
Future!Amy: I bet you would.
- Buffy Speak: The wibbly lever.
- Car Meets House: This happened to Amy the one known time that Rory let her drive to the end of the street. She ran into an "unexpected" house.
- Continuity Nod:
- Amy's line "Okay, kids, this is where it gets complicated," is the same one she used in "The Big Bang", in similar conjunction with confusing time travel.
- Also, Classic Who fans will remember an infinite loop of police boxes appearing in the TARDIS from Four's final episode, "Logopolis".
- Big Finish Doctor Who has the Eighth Doctor story "The Chimes of Midnight", where the outside of the TARDIS is in a space loop.
- The TARDIS's emergency-lock-onto-the-nearest-safe-space feature previously appeared in the Classic Who episode "Terminus". Whether it worked better on that occasion depends on whether you prefer being trapped in an infinite recursion or being surrounded by space lepers.
- Also, bananas.
- Future Amy's explanation of her need to maintain the Stable Time Loop ("I'm just repeating this, and this, and this") is quite reminiscent of the Doctor explaining the same thing in Moffat's own "Blink".
- Also one to "The Vampires of Venice" where an unnerved Rory talks to the Doctor working on the TARDIS in steampunk goggles. Since Rory Took a Level in Badass, the Doctor now trusts him to wear the steampunk goggles and work on the TARDIS.
- The one and only time (so far) we've seen Amy behind the wheel of a vehicle was in "Amy's Choice", where there was a house involved. And Rory doesn't know this, because he was dead at the time.
- Distracted by My Own Sexy: Amy gets distracted checking her future/past self out. This episode even provides the page quote.The Doctor: Ohh, this is how it all ends. Pond flirting with herself. It's true love at last.
- Distracted by the Sexy: Rory becoming distracted by Amy's skirt causes him to drop a thermo-coupling... though it's not his fault the floor is made of glass.
- Do I Really Look Like That?: Present!Amy asks Future!Amy.
- Drives Like Crazy: Implied with Amy, as mentioned above with the "Unexpected house".
- Getting Crap Past the Radar: Skirt and a glass ceiling... Moff, you've outdone yourself!
- Girl-on-Girl Is Hot: Amy flirts with herself. Rory approves.The Doctor: So this is how it all ends. Pond flirting with herself. True love at last... oh, sorry, Rory.
Rory: (staring) Absolutely no problem whatsoever.
- Hypocritical Humour: Amy slaps Rory for his implied Twin Threesome Fantasy mere moments before flirting with herself.
- Large Ham: Amy's melodramatic, "I'm you, from your future!" is revealed to be this when it turns out she's just a few seconds ahead in the timeline.
- Metaphorgotten: "We're just entering conceptual space. Imagine a banana. Or anything curved. Actually, don't, because it's not curved or like a banana — FORGET THE BANANA!"
- Mind Screw: That "banging on the head" you feel is Moffat throwing the Timey-Wimey Ball through a TARDIS and hitting your future self with it.
- Panty Shot: Downplayed since we don't see it, but presumably Rory did thanks to the aforementioned skirt and glass floor, presuming she's wearing panties of course.
- Rule of Funny: All the humor about timey-wimey loops is wrung out here, starting with Amy repeating something that her future said.
- Screw Yourself: Amy is flirtatious with her future self, as the Doctor — and the fandom, no doubt — notes.
- Stable Time Loop: "I'm just remembering what I heard myself saying when I was standing where you are now and repeating it. I'm just repeating this too. And this... and this..."
- Steampunk: Rory was rocking some pretty steampunkish goggles.
- Techno Babble: Use the Wibly lever to exit conceptual space that is not at all like a banana.
- Temporal Paradox: How, exactly, did the Doctor know it was the wibbly lever? You could try to explain this by saying that any other one would have killed all of them, thus breaking the loop, so any loop that formed would have had to include that particular lever, but that would only make it less plausible. Major holes in all of causality aren't at all rare in the Whoniverse, so no time loop was really warranted, unless the timeline was fixed inside the TARDIS which would mean that they couldn't change it if they tried but then how could the inside drift from the outside or the characters enter the AAARRRGGGHHH!!!
- It can be explained on the grounds of quantum immortality. The only surviving Doctor is the one that would have pulled the Wibbly Lever, so he's the one that emerges from the box.
- Time-Travel Tense Trouble: Rory is particularly confused by this trope when time and space go wibby-wacey.
- Timey-Wimey Ball: This episode utilizes time-travel for maximum confusion. After all, Moffat is the Trope Namer.
- Took a Level in Badass: The Doctor trusts Rory to do delicate TARDIS repair work. It takes a certain level of trust to let another man mess around with the engine of your motor, especially when said motor has previously proven capable of blowing up time.
- Twin Threesome Fantasy: Amy's repeated flirting with her future-self gets the Doctor to snark that it's "true love at last" before apologizing to Rory. Rory doesn't care. In fact, he seems to be very into the idea.
- Women Drivers: The last time Amy drove a car, she hit an "unexpected" house.