I was watching Glengarry Glen Ross (1992), a movie that's held up pretty well. It's fairly faithful to the play, as you might expect, since David Mamet adapted his own work.
Anyway, while watching, I was thinking has any cast ever been filled with so many Oscar winners and nominees (not necessarily at the time, but looked at from today)? To demonstrate, here are the actors who play the main characters, along with their awards:
Alan Arkin: one Oscar, four nominations
Alec Baldwin: one Oscar nomination (and he's won some Emmys)
Jack Lemmon: two Oscars, eight nominations
Al Pacino: One Oscar and eight nominations, including one for this film
Jonathan Pryce: no Oscar nominations (but he has won a couple Tonys)
Kevin Spacey: two Oscars
Perhaps there have been more Oscar nominees in some films, but never this high a concentration. The Oscar-to-leads ratio is off the charts.