Continuity mistake: When Al comes home, he finds a written message from Peg saying that she, Kelly and Bud are at Marcy's house performing the Village People. However, Peggy couldn't have written the message because when they agreed to play the Village People, they went over to Marcy's immediately. (00:04:50 - 00:06:10)
Continuity mistake: When the chain is cut with Marcy by Al to release him from the pole, later in the newscast in the background they are showing the cut chain. When on the news, it shows the chain was cut about a foot from the goal post. However when you watch the guy cut the chain for real, he cuts it flush with the pole.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.