Some more movies with movie audiences:
 
The original THE BLOB.
SULLIVAN'S TRAVELS (I mentioned this earlier as a film-making movie, but it's
also a film-watching film)
FURY (a real classic that revolves around watching newsreel footage; Fritz
Lang's first English language film)
The new BRAM STOKER'S DRACULA.
MISSION TO MOSCOW (1943) (it's not a particularly important scene in the film,
but there is a scene in which American citizens watch a newsreel about the
Soviet Union and have a critical discussion about its contents while it runs.
One of the few representations I know from that time of a truly critical
film audience)
TAXI DRIVER (scene in the porno theater)
AMERICAN WEREWOLF IN LONDON (also a minor scene in a movie theater)
GREMLINS (a film I hate . . . but it's climax IS in a movie theater)
 
I'm sure I can think of many, many more, but I'll stop for now.
 
Ben Alpers
Princeton University