When Michael does his try-out for Lisa, the arena is bone dry. He immediately has a conversation with Lisa, and the arena is suddenly wet. He then asks Mark to see his act. When Mark does his act, the arena is once again bone dry.
When KITT is doing stunts the external views show a regular steering wheel. Inside KITT is the custom steering wheel.
When KITT performs the jump over the moving truck and car, he noticeably nosedives towards the ground as he lands, where the stunt went slightly wrong in filming; the sequence is edited with other shots to make it look like he had a perfect landing. Later, when Michael is drugged, the same footage is used, again showing the nosedive, and the episode's opening teaser also ends on the shot, again being very noticeable.
When KITT balances himself on two wheels, it is clearly visible that the person at the wheel is not David Hasselhoff but his stunt double and there's a dummy in the passenger seat.
Several conversation scenes set at the arena very obviously were shot with the aid of lights for filming, with tell-tale signs such as shadows giving it away.
Although KITT is said to be impervious to damage, a dent can be seen in the door as it opens/closes at about 16 minutes in.
When the police car at the beginning starts to chase after Michael and KITT for "speeding", you can see a cameraman in the back seat filming over the actor's shoulder. This footage he shoots is the next thing we see.