During the first preview, Riggan learns that Mike is drinking real gin on stage. He replaces it with water and in the middle of a monologue, Mike completely breaks character and has a meltdown as he smashes the set.
Mike: This set is fake, the bananas are fake, there's fucking nothing in this milk carton! Your performance is fake! The only thing real on this set is this chicken, so I'm gonna work with the chicken! [the cabinet collapses as he slams the refrigerator door]
"Leslie...Play with my balls."
Riggan being locked out of the theater in his underwear and having to walk through Times Square with thousands of people watching him before he makes it to the front entrance.
The fact that he has to walk into the auditorium and execute his part. He mimics knocking on a door and he shapes his hand into a gun - and Lesley and Mike, trying to be in character and adhering to the script, continue to allude to a gun.
Even better. Since he's waaaay too far from the door and is supposed to knock, he just screams loudly "KNOCK, KNOCK, KNOCK!". Instead of doing what any actor with a minimal training would do: skip the knocking and go for the yelling.
Riggan's flight sequence, which ends with a cab driver yelling for a fare that his client won't acknowledge.
Just before the flight sequence starts, he's standing on the edge of a building and a random woman calls out.
Woman: Hey! Is this for real or are you shooting a film?
Riggan: A film!
Woman: You people are full of shit!
A bittersweet one at the end:
(Sam brings him some flowers)
Riggan:(laughs)
Sam: What's so funny?
Riggan: I can't smell it.
Birdman sitting on the toilet.
The ENTIRETY of the tanning fight between Riggan and Mike.
Riggan: Just find me an actor. A good actor. Give me Woody Harrelson. Jake: He's doing the next Hunger Games. Riggan: Michael Fassbender? Jake: He's doing the prequel to the X-Men prequel. Riggan: How about Jeremy Renner? Jake: Who? Riggan: Jeremy Renner. He was nominated. He was the Hurt Locker guy. Jake: Oh, okay. He's an Avenger. Riggan: Fuck, they put him in a cape too?
Meta: Birdman won the Best Film Award, while Michael Keaton won the Best Actor Award. Who did they win them from? The Gotham Awards.
Yet another meta moment of funny: Throughout the whole movie Edward Norton is a bossy prima donna actor who keeps meddling with the director, similar to how he commonly does this in real life. To the point where, during rehearsal of this movie Norton unknowingly started meddling with the director over the script. When called out on this, Norton didn't even catch the irony at first!
