In some versions of the opening credits, most notably the version in which Toody and Muldoon are playing checkers in the car, the bubble light atop the squad car jumps when the car shakes. It should be bolted in place.
The squad car doesn't have a windshield. During the opening credits where they're playing checkers, the board bumps the wipers.
No consistent spelling for surname of character played by Al Lewis. In credits, it is listed as Schnauser, but name stenciled on character's locker is Schnauzer - with various spelling appearing whenever name is seen printed throughout series run.
Obsolete 19th-Century single-action revolvers were often shown carried in police service holsters.