Every time KITT drives into the mobile headquarters we can clearly see that the car just barely fits, with only a few inches clearance from each side, yet Michael is able to swing the door open and get out.
In almost every episode the landscape seen through the car-windows when Michael is talking to KITT while cruising doesn't match the exterior views of KITT driving along.
In the first episode with KARR, there's an explosion after he goes over a cliff, implying he blew up, yet in the second he is found completely intact except for an unplugged wire.
In the episode when KARR first appears, it is physically identical to KITT: All black body, red scanner. However when KARR is discovered buried on the beach in a later episode, it had a black and silver body and a yellow scanner.
During the entire series, "turbo boost" is used both for high-speed chases as well as for jumping. "Turbo boost" is supposed to be used for both according to the series canon.
In many episodes, David Hasselhoff's stunt double looks absolutely nothing like him and is on screen long enough to be obvious.
In many episodes, the cars used in crashes or in scenes where a car is falling in a lake are clearly model-cars "driving" through miniature landscapes.
Throughout the series due to budget constraints, several scenes and special effects shots are lifted from well known movies from the 70s and 80s and even from earlier Knight Rider episodes.
The "tires screeching on pavement" sound effect is often added while KITT is peeling out on sand or rounding a corner on sand/gravel/grass. Screeching sounds would certainly not be heard while driving on such surfaces.
Throughout the series, several actors play several different characters, with minimal attempt at disguising this.
The copyright date at the end of the credits on the first (pilot) episode shows the roman numerals MCMLXXVII (1977) instead of MCMLXXXII (1982). Some people have suggested that this may have been when the idea was conceived rather than produced.
Throughout the series, K.I.T.T.'s cameras take pictures from outside the possible viewing angle of any camera that can be mounted on K.I.T.T.
Whenever K.I.T.T. taps into electronics, the same electronic circuit board is shown irregardless of what type of electronic device it is.
Whenever driving in the rain, KITT never has windshield wipers on.
When using 'Super Pursuit Mode', several projections pop out of K.I.T.T.'s frame. These projections should still be visible as outlines when retracted, but the frame is solid with no outlines.
KITT is supposed to have an air-plane style steering wheel. However, in many episodes, the top portion of the stunt-car's normal, round steering wheel is visible through car's windows.