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.
Revealing mistake: When the chain is cut from Al's wrist, you can see and hear that it's plastic not metal. (00:02:28)
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.