Cheese, Cues and Blood - S6-E4
Continuity mistake: When Kelly shakes her head no to the guy she is playing for $10,000, he misses the shot and the ball stops at the far end of the table. When Kelly goes to take the next shot for the win, she is hitting the cue ball from the other side.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.