Other mistake: The email that starts it all for Sid Straw, the announcement from the University of Pennsylvania that he has been chosen to serve on the reunion planning committee, starts off with a nonsensical sentence that no one from U Penn would have ever typed. It's obviously the product of a studio runner whose work no one bothered to proofread. (00:01:15)
Revealing mistake: In the scene where Dave (Alan Tudyk) is brushing off Sid (Tony Hale) at the reunion, the camera from slightly behind captures jaw movements that don't match his speaking, and he continues speaking when there is no jaw movement at all. (01:47:00)