When Richard Pryor is on the phone with Bill Cosby during the water leak, his shirt gets wetter with each scene. However, when he gets off the phone, his shirt is completely dry.
Bill Warren made a 1:30 lunch reservation for him and his ex-wife Hannah. After lunch, some time at the beach, and post-beach freshening up, Hannah says "It's 2:30; do you wanna call Jenny, or shall I?" It wouldn't be possible for all that activity to have taken place in just one hour.
In the bathroom, post-Oscars, Diana Barry fails to secure her nightdress at the neck. When the shot changes, it's now fastened.
Sidney Cochran admonishes his wife that they have a 10:00 AM flight. He also loses count of his Librium, quipping "if I'm not up at 9:00 AM, I've overdosed." It would not be possible to wake up at 9:00 AM and travel from Beverly Hills to LAX FOR A 10:00 AM departure.