You Gotta Know When to Fold 'Em (2) - S4-E17
Plot hole: Al hasn't got enough cash to pay for a pizza and Peggy overmaxes his credit cards. But somehow he manages to buy three flight tickets for Chicago-Las Vegas. Where'd the money come from? Also, when his card is declined, he calls the pizza shop back (they call him "no tip" Bundy), and somehow they know where Peggy maxed out the credit card. (00:05:15)
You Gotta Know When to Fold 'Em (2) - S4-E17
Factual error: Bud and Kelly wouldn't be allowed to go in a casino in Vegas because they are both under 21.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.