When Charly Matteï is driving and looking for an empty parking slot, his car has a major crack in his windshield. After finding a spot and shutting down the engine the crack is gone.
Toward the end of the film, a man is eating a slice of pizza and telling a young man playing a video game what to do. He turns around and the slice he is eating is suddenly less eaten than it was before.
The kid wraps the grip of the pistol with electrical tape. To keep the grip from holding fingerprints, he should have used friction tape, a coarse fabric tape.
Charly's right arm is supposed to be paralyzed yet, whenever he is riding the motorcycle, he works the controls as if his arm and hand are perfectly normal.
While Mattei is in the hospital the retrospect shows a young boy wrapping the gun handle with electrical tape. The idea is to make it impossible for the police to pick up fingerprints after the killing. However, he's using the wrong kind of tape - the smooth one instead of the sticky rough one - which renders the whole process useless.