Sixteen Years and What Do You Get - S1-E6
Other mistake: Al has his elbow in the caviar yet when he lifts it up out there's nothing on his shirt. Its clean and dry.
Sixteen Years and What Do You Get - S1-E6
Plot hole: Peg maxes out the credit card buying Al anniversary gifts and hiring a caterer. When Al tries to buy a watch for Peg it's declined. Later on Kelly somehow uses the credit card and is able to buy the expensive picture frame at the same store Al tried to buy the watch.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.