When Michael first visits the lumber mill, some of the shots show clear weather, while in other shots of the same time frame, it is raining lightly.
K.I.T.T.'s pursuit indicator changes colour throughout the show, thanks to stock footage from different periods of the show. First violet, then red, then white.
When KITT changes from convertible mode, the roof interior has a red/orange release handle not seen in regular mode. Also, all the overhead buttons known to be mounted to the headliner are absent.
When Michael and KITT (in Super Pursuit Mode) are chasing Samantha, they pass by Erik Whitby and his group. It is obvious that although the digital speedometer read 250 mph+, they are not traveling nearly that fast.