The length of Omar's hair, the character played by Mekhi Phifer, shifts from short to long and back to short again by the end.
When Larry, Cheryl, Jeff and Susie are dining at the 25th Anniversary party and Larry wants to leave before dessert, their dinner plates are present, then disappear, and are present again between shots.
When Larry is talking to Marty at the party a clarinetist is seen playing (or miming) in the band in the background but the music we hear has no clarinet part.