Treehouse of Horror XIV - S15-E1
Continuity mistake: When the younger Professor Frink is receiving and wearing his Nobel Prize, his father goes nuts and starts stealing people's brains. The younger Frink figures out that kicking the elder Frink in the crotch will stop him. When he does, and the elder Frink falls off the stage, he is wearing the Nobel Prize, not the younger. (00:15:00)