Reporter: Tell me, how did you find America? John: Turn left at Greenland.
After we've heard Paul answer questions with "No, actually, we're just good friends" several times:
Reporter: Do you often see your father?
Paul: No, actually, we're just good friends.
During the opening, three of them - John, George, Ringo - are running throughout the train station, while Paul calmly sits and waits for them to catch up to him and his gramps. And Paul does it by wearing facial hair to avoid getting spotted by the squeeing fangirls.
John's wordplay with a flustered Millie who thinks she recognizes him as who he is. When he's done confusing her, she's convinced he doesn't look anything like himself.
John:[To himself, sour]She looks more like him than I do.
Even better, Lennon apparently improvised this line.
"Hey, mister, can we have our ball back!? Mister, c'mon, Mister! Can we have our ball back?"
Even funnier when they appear outside, running along beside the train.
Also just before when they all line up and pull silly faces at the nasty man.
And a second later they're shown walking down the aisle past the train car, carrying Ringo, with the implication that we're seeing a further attempt to irritate their fellow-passenger.
Paul's grandfather escaping during "She Loves You", then coming on stage via the elevator - only to be pulled offstage by George (and kicked in the rear by Paul for good measure!)
TV Director: That's wrong. Surely, that's wrong. (into headset) No, not you. (on PA) GET. HIM. OUT.
Pretty much anything John says or does throughout the movie.
Special mention must go to his truly epic scene in the bathtub. He cheerfully ignores the conversation going on ten feet away from him, preferring instead to play a highly noisy and splash-y game with toy torpedoes.
"Rule Britannia! Britannia rules the..." SPLOOSH
Bonus points in that scene go to George's utter lack of surprise.
Torpedoed again, eh?
"If I Fell". They sing it to Ringo.
The entire scene's worth of "Can't Buy Me Love." Of particular note: shots of John, Paul and George, each jumping spectacularly into the air...followed by Ringo readying himself for a similarly gigantic leap and doing this pathetic little hop with his arms at his sides.
An iconic exchange at the end of the scene:
Man: I suppose you realize this is private property?
George: Sorry we hurt your field, mister.
The total lack of reaction on the part of all four Beatles to the revelation that there's a man locked in the closet. Even better, Ringo and George separately walk up to the closet, look inside, close the door and casually walk away, although they appear to be mildly concerned.
George:[After checking the closet on Ringo's claims of a man being inside] He's right, you know. John: Well, there you are.
This line, coming from Ringo:
"There you go, hiding behind a smoke screen of bourgeois clichés."
Ringo's reaction after he accidentally causes a well-dressed woman to step right into a sinkhole.
"Ringo, what are you up to?" "Page five."
The sight of all the young girls swooning and going nuts over the Beatles during their end concert.
Simon Marshall's assistant tries to whisper to him "That's George Harrison". Not listening, Simon sternly responds "Don't breathe on me, Adrian."
During the sequence when the cops are chasing the Beatles, they run several times by a guy trying to break into a car. The first two times, the guy stops and looks casual when they pass; the third time he doesn't bother stopping and manages to get into the car. As soon as he gets in, the cops pile in and ask him to follow the boys. The guy, clearly frightened to be busted, pulls down his hat really low and drives as told.
When Shake is denied entry into the casino, he says this: