Another one with limited pre-one night set up is The Night Before, with Keanu Reeves and Lori Loughlin. He’s a dork, she’s popular and for reasons that now escape me but made probably thousands of 80s teen comedies happen, she has to go to the prom with him. Debacles ensue, as Keanu gets drunk in a seedy (read: urban black) bar, sells Lori Loughlin into white slavery, and then gets the car stolen.
God, I love Can’t Hardly Wait!
Thank you!
No, thank you! Finally, someone who has a clue. I also seem to recall “Killer Klowns from Outer Space” took place over the course of one night.
How about Die Hard and Die Hard II?
That brings to mind Murder by Death.
I was trying to remember if it was exactly one night, since it was supposed to be a weekend and they went to bed, but you’re right - they all leave by dawn the next morning.
Technically, Back to the Future takes place in a single day. 
Had to mention my favorite movie.
52 posts without a coding mistake, and now this!
Lots of “thrillers” happen in a short time span: Terminator took around one day… One False Move, Panic Room, Trespass, Pelham 1-2-3, Run, Cellular, D.O.A. (both of 'em!)… the actual timeline of The Usual Suspects is the time it took to interrogate Kevin Spacey.
Dr Strangelove
Who’s Afraid of Virginia Woolf? or “When Dinner Parties Go Wrong”
Who’s Afraid of Virginia Woolf?, both film and play, take place in one night.
Harold and Kumar
Eugene O’Neill’s Long Day’s Journey into Night
Yes, I’m a dork … she went to the prom with him because she lost a bet.
And both 200 Cigarettes and Go take place in one night. All my other really good ones have already been taken.
To bend the rules a bit:
The Wizard of Oz, technically.
The Hudsucker Proxy, as it begins and ends on the same night and the rest is a flashback. Though I suspect quite a few could fall into this category.
Also, if days count: The Breakfast Club and Ferris Bueller’s Day Off. Twelve Angry Men, too.
Ok, ok, I cheated and looked up this previous thread of mine on the same topic.
[Totally Off Topic]
Hey Garfield, have you checked your email lately?
[/TOT]
Midnight Madness: early 80s scavenger-hunt movie with David Naughton and a very young Michael J. Fox.
Don’t forget Stephen Furst.
In the category of one day not night movies, there’s One Fine Day with George Clooney.
I cannot fathom why nobody has yet mentioned the absolutely terrible Warriors