Revealing mistake: In the warehouse, after Michael calls him, when KITT busts through the door, the plastic sheeting used inside the driver's window to hide the stunt driver is noticeable.
Other mistake: When Michael and Marty are being chased and shot at, K.I.T.T jumps over the top of a hill. In the next shot of K.I.T.T driving away, you see a wheel trim rolling down the hill which has fallen off K.I.T.T. (00:39:45)
Answer: KITT didn't choose to go off the cliff in Goliath Returns, it just happened as he tried to avoid Goliath. Just 'cus it happened, doesn't mean It's gonna cure his fear of "flying"