When K.I.T.T. jumps over the bull, you can clearly see the wheel running over the head of the bull and it bobbing back and forth... obviously plastic.
In the climax water from the reservoir is rushing through the land until K.I.T.T. uses his retro rockets at a canyon to create an avalanche of rocks creating a new dam. However there is a brief shot of the water flow showing the newly formed dam of rocks before K.I.T.T. arrives at the canyon to create it.
When K.I.T.T. jumps to further unnerve the bull, the car lands with everything all but flying apart, exactly what could be expected from any such destructive stunt. Immediately afterwards, however, of course K.I.T.T. stands there looking like a spotless showroom model. But that doesn't change what was seen. And since K.I.T.T. isn't supernatural and Bonnie never got around to adding a gizmo for instant car repair...
The stretch of film showing the breaking dam wall, the river in flood and the collapsing mountain, was taken from Superman (1978), a wide screen motion picture, edited in just like that, and therefore appears in a (distorted) wrong aspect ratio.
K.I.T.T. scares off the intruder while on guard duty by moving forward and flashing its lights. A visible pull bar can be seen under the bumper.