I'll See You in Court - S3-E10
Continuity mistake: While they are in court, Steve is talking about the case and the clock says 12:30. Next time he's seen and talking about privacy to the jury, the clock says 11:30. Then when done talking, the clock says 3:00. The very next scene as the court proceedings are going forward, now the clock says 12:29. Next scene says 4:32. Than backwards again. The clock is moving forward and backwards throughout the entire scene.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.