What film's cast has won the most total Oscars?
This means Oscars in the four acting catergories, not honorary or special Oscars and not Oscars in other categories such as writing or directing. It also means most total Oscars, so if Tom Hanks is in a film, that counts as two Oscars.
Spoiler
Jack Lemmon (2), Tim Robbins, Whoopi Goldberg, Cher, Louise Fletcher, Joel Grey, Angelica Huston, James Coburn, Marlee Matlin, Susan Sarandon, Rod Steiger and Julia Roberts (1 each). Syndney Pollack was also in The Player which would give it an unofficial total of 15. Many of these were cameo appearances.
If you want to limit it to regular billed cast with significant roles, then it's How the West Was Won (10):
Walter Brennan (3), Spencer Tracy (narrator)(2), Henry Fonda, Karl Malden, Gregory Peck, James Stewart and John Wayne (1).
BTW, in August, there will be a new DVD version of How The West Was Won. The existing DVD and most of the prints shown on television look terrible. This one is cleaned up and looks terrifice with the lines marking the edges of the Cinerama strips (which means the film on TV or current DVD looks like it's been divided into thirds) are gone. Also, the Blu-Ray version will have a curved screen option in which the film looks as it did on original Cinerama screens (like an hourglass on its side), removing the distortions that occur when it's projected on a flat surface.
Additional trivia. What was the only other dramatic film (not travelogues or documentaries) that was made in Cinerama besides West?