Continuity mistake: When Kersey goes into the post office and his girl is waiting in the car, Fraker and his goon knock her out and shove the car down the hill. As it goes down there is a view of the back of the car and the reverse lights are on. Then as it is about to hit the other car, the lights are now off.
Continuity mistake: One car gets shot at, and bullet holes are all over it, in the sides/windshield etc., but in the car crash, tumble and explosion, they are gone.
Continuity mistake: Charles Bronson throws a hood off of a rooftop, when he lands on the car below he is in a sitting position. Later when the police are looking at the body the hood is laying across the top of the car.
Continuity mistake: Martin Balsam shows Charles Bronson a .30 cal. machine gun that is in a cabinet. Later, Martin goes to get the gun to shoot the gang members, but the gun he gets is a different kind of gun, than what was shown earlier.