Revealing mistake: During the first shot of Larry being pushed out of the car, it's blatantly a stunt double who is taller, thinner and has shorter hair than the actor.
Continuity mistake: During the family dinner, the level of the wine in all the characters' glasses changes from one shot to the next.
Continuity mistake: When Gil talks to Karen in the van about his dazzling Dave and being tense, the red and white registration sticker is visible at the lower right corner of the windshield. When Gil and Karen's van is totaled that registration sticker is conspicuously gone. (01:15:40 - 01:16:40)
Factual error: In the opening scene at the baseball game, the announcer thanks the crowd for coming to see the St. Louis Cardinals. The fans are sitting in yellow seats, but all of the seats in Busch Stadium in St. Louis are red.