Continuity: When the "fight" starts and they crash through the restaurant window, the lady who stands and screams on the left, does so twice as the camera angle changes.

Deliberate "mistake": At the end fight scene, when they are in the barn one of the men falls crashes through the wall when they get hit, spilling the fight to the outside. Unless the barn's walls were made of cheap plywood, the wall would not have given away so easily. Obviously done for dramatic purposes.

Revealing: It's obvious that when Clyde disassembles the car, the car has been pre-disassembled so Clyde would have an easy time taking it apart. Specifically the doors and trunk lid.