David Hasselhoff is more heavily built than, and has a thicker neck than, the actor who portrays Michael Long in the opening sequence of the show.
When Wilson shoots at K.I.T.T. it ricochets and hits the helicopter but when you see shots of the helicopter damaged, it is smoking on the opposite side. Also when the helicopter comes into land you can clearly see the box attached to the side of it.
Near the end, Michael Knight has been shot in the shoulder. As he is driving KITT, the shoulder he has been shot in swaps sides two or three times.
The nose of K.I.T.T. changes multiple times in the movie. At some point the nose has lights in it, other times the nose is more armored looking and thus has no lights at all. The nose consists of black metal plating
When K.I.T.T. is first introduced, the front end is a stock Pontiac Firebird Trans Am that is blackened out. This is seen throughout the long highway drive to Silicon Valley. But when Michael and Kitt arrive at their destination, the front end is the custom version used throughout the entire series.
On Michael Knight's driver's "new" driver's license, he is listed as being 5'6 with brown hair, brown eyes. In real life, the David Hasselhoff has blue eyes and is app. 6'4. By comparison, everyone else on the show would be really, really short.
When KITT is doing the 'doughnuts' at the intersection you can clearly see it has a normal round steering wheel.
Obvious dummy substituting for Buddy during the demolition derby.
During the demolition derby, KITT can be seen several times having a normal round steering wheel.
Obvious stunt driver during the demolition derby, when KITT is driving on two wheels.
When KITT breaks Michael out of jail, you can see the wall is made out of cardboard when Michael and KITT exit.
The copyright date at the end of the closing credits is wrong. It reads "MCMLXXVII" in Roman numerals, or 1977. The "V" should have been another "X," which would have given the correct date of 1982.
When Michael calls Devon to tell him where he is, Michael asks him why he doesn't know. Edward Mulhare starts to say, "I'm not psychic" but then, after saying the initial "s" sound, switches to "clairvoyant".
KITT returns to Michael at the gas station after leaving the thieves at the police station. As the driver-less KITT pulls up to Michael, you can see the camouflaged driver, dressed as the car seat, drop his hand off the steering wheel as the car comes to a stop.
A stunt driver wearing a hood is visible inside KITT when the car inches forward behind the guard as Michael is trying to escape Comtron.
Camera and cameraman are visible in the car when Michael gets shot.