When the bomb is taken from the marina area, the timer reads 15:00:01. When the bomb is seen in the parking garage, it has just under 13 hours on the timer. The bomb is set to explode at noon the next day, yet it is full day light outside, and since Michael visits Fenton after 7:00 p.m. while it is full dark outside, the bomb must have been transported earlier that afternoon. The timer should have started at 20 hours or so.
When the bomb's countdown timer is seen, it is making a ticking sound, but it is a digital timer and digital timers don't tick.
There are neither toilets nor sinks in the prison cells. Prison cells in the U.S.A. are always equipped with both toilets and sinks.
The license plates of the cars involved in the action (except KITT's) are white with green lettering with no state name. But all the parked cars and ones not involved in the action are regular California plates.
When KITT jumps the prison walls, the outside wall of the jail is seen receding as they escape. It is smeared with graffiti. No operational American corrective institution would tolerate its facade to be defaced. Obviously the location that had to be used would have been an old deserted institution, but this gives the game away.
When the bomb clock has 8 minutes left, KITT says the nearest uninhabited place is 45 miles away. McCord says "we'll never make it in 8 minutes" and Michael replies "don't be too sure." To travel 45 miles in 8 minutes, KITT would need to drive 337 miles per hour. KITT's display only shows 150 mph at most during this scene (170 mph during the turbo boost).
When the bomb finally explodes on a dirt road, the resulting fireball is not even close to being as destructive as the government officials warned. They were trying to save "thousands of lives" but an explosion of that size from inside the trunk of a Cadillac parked in a steel-reinforced concrete garage would have, at worst, taken out a few dozen cars and maybe a half-dozen people who happened to be close enough to be fatally injured.
When Michael asks K.I.T.T. to locate all the police cars in the area, he states that they are surrounded before seeing the image on the map.
Michael chides Peter McCord by looking at the "nice legs" on the photographs of his model daughter pinned up against the wall of the cell. But the pictures were mostly of shampoo and hair-styling commercials. Nothing remotely leggy.
When Michael and Peter have about 15 seconds to get into KITT and drive away from the bomb, Michael pauses to close KITT's trunk. KITT should have done that itself (or told Michael and Peter to jump in the trunk then drive itself away).