Continuity mistake: When Michael is in K.I.T.T and he is taking the professor's blood pressure, the boot is open. When it goes to an outside shot of K.I.T.T driving away it is closed. (00:03:50)
Continuity mistake: When Michael rescues Bonnie and asks K.I.T.T to meet him, one minute it is night time, next scene bright daylight. If it was morning it wouldn't be that bright. This is where they have possibly used footage from a previous episode. (00:26:20)
Continuity mistake: When they arrive at the museum and start to unload K.I.T.T it is raining fairly hard. When it cuts to Bonnie and the Professor and the woman it isn't raining. This keeps happening throughout the scene. (00:38:15)
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"