Real Genius (1985)

Other mistake: When Mitch calls his mom asking to come home Kent and his friends hear him make the call. Mitch then has some conversation with his mother. Kent and his friends begin recording the conversation at the point where Mitch says "I want to come live with you". The problem is that when the recording gets played back in the cafeteria the conversation is replayed from the beginning which was before Kent had begun recording it. (00:45:50)