(at around 38 mins) There is bird mess over the windscreen of the car seen from inside the car when there is the pickup of the gun salesman. When the camera films from in front of the car, the bird muck has disappeared.
When Alma is taking tennis lessons, there are a lot of balls on the court between her and the net. When the camera moves behind her, looking at the net, they've all disappeared, and the instructor's bucket of balls is fuller than it was.
When Earl and Jack show up at Mailer's house, the back windshield of the car, which was shot up on the highway, is completely intact.
When Bett goes back to the motel room after calling her father, on the exterior shot she stops at the room's door to get her keys, and the exterior doors and frames are blue. In the next shot, from inside, Bett opens the door, and the door frame is white, and looking beyond her, it's not the outside of the motel at all but another room.
'Ambulance' is printed backwards on the front of ambulances as a safety measure - so the word can be more easily read in the rearview mirrors of vehicles in front of one trying to get through traffic.
Indeed, it is a common safety measure and, therefore, is not a Goof.
Indeed, it is a common safety measure and, therefore, is not a Goof.
A killer fires a revolver with a silencer on the barrel. The gun would still make a loud sound due to the gap between the cylinder and the barrel.