When Joe Mantegna and Don Ameche "escape" from the mobster's mansion they have to hot wire the car they use, as they can't find a key. When they're prevented from leaving the gas station shortly afterward, the owner reaches in and removes the car key to keep them there.
This slip up was so obvious one would have to wonder if two different directors were involved, one handling the "escape" and the other the "gas station" scene!