Breaking up is Easy to Do (2) - S11-E15
Continuity mistake: Before the dinner date, Peggy takes a plate of raw meat out of the dishwasher. Bud and Kelly go to help her put it on the stove, but Peggy's plate is now empty and the meat is on another plate already on the stove. Yet strangely, Bud and Kelly take the empty plate from her anyway and put it on the stove next to the other one.
Breaking up is Easy to Do (2) - S11-E15
Revealing mistake: When Al falls on the bed with the shoe and puts the hole in the water bed, the shoe doesn't hit the bed anywhere near where the water starts to shoot out from.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.