When K.A.R.R. (evil counterpart of K.I.T.T.) plummets over a cliff to its apparent demise, the car shown in the wide shot is not a black Trans Am, nor does it even resemble one. It is in fact stock footage from The Car (1977), the car from which is another George Barris custom build. The producers own the rights to both Knight Rider and The Car.
Near the beginning, just before KITT complains to Michael about the late hour, the shot over Michael's shoulder towards the car's dashboard shows red sleeves on the driver's arms, under the leather jacket. The next shot, a front-on view, shows Michael wearing a blue button-down shirt under his jacket, with no red in sight.
Near the end, when Michael and Bonnie are riding in KITT in the final showdown with KARR, the scenery changes from full daylight to almost nighttime between shots.
Michael is atop K.A.R.R then jumps onto K.I.T.T to continue the chase. The scene continues to switch between interiors of each car. In one scene you can clearly see Michael's boots in the rear windscreen behind Bonnie, even though Michael is now chasing in K.I.T.T in the next cut
After Michael climbed into KITT during the chase, interior shots of Michael show the background of a city, yet at that time they are in a forest-only area.
At the end Michael, Bonnie and KITT are driving on the left side of the road to make KARR turn. But when they show Bonnie and Michael's faces you see cars going past them like they were driving slow and on the right side of the road.
When KARR Turbo Boosts over KITT to exit the warehouse, he is landing on a platform hidden off-screen to the right, rather than on the ground.
While Rev and Tony case the lab, two blue lines are visible on multiple camera angles.
In the part where the two criminals are seen robbing the building with the large "COINS" sign, right before K.A.R.R. hits the entrance, you can see that the car has stars on it. It's a shot from episode 'Slammin' Sammy's Stunt Show Spectacular'.
When K.A.R.R. and the two crooks are on a crime spree, an obsolete Los Angeles Police Department car is seen, stock footage from 'Adam-12'.
When K.A.R.R. is flying of the cliff into the beach, the car used for the stunt is not even a Trans Am. it's a completely different model.
Although accompanied by high-revving engine sounds, KARR is moving along at only about 5-10 miles per hour when Michael (or his stunt double) jumps onto it.
K.I.T.T.'s red voice-modulation lamp [he doesn't have his better-known snazzy-looking L.E.D. 3-column bar-graph-display modulation indicator yet] sometimes doesn't flicker in sync with his speech, the way it always does at other times.