Visible crew/equipment: When Peggy enters you can see the shadow of someone's head at the left edge (the kitchen). It can't be anyone of the actors. (00:12:05)
Continuity mistake: The out of order sign on the toilet changes position between shots. It's level at first. Camera cuts to other men. When it cuts back to Al it is tilted. (00:18:18)
Continuity mistake: When Al and Peg are on the couch, the ice bag changes position.
Answer: It was one of the hoses connected to the engine, nothing specific, but to indicate that Al tampered with the vehicle.