Oldies but Young 'Uns - S5-E17
Other mistake: Just before Charlie and his son leave Peg says "Charlie, my watch". Implying that he took it off her wrist. Yet during the whole scene she didn't have a watch on her wrist. It appears in his hand out of nowhere.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.