Deliberate mistake: As Nancy and her Mum are leaving Rod's funeral, you can see the shot of them leaving the funeral has been sped up. Watch the Volvo "jerk" as it pulls away as the speed is rapidly increased.
Deliberate mistake: When the truck is slamming numerous parked cars on a residential street, it sideswipes a parked Dodge Aspen (white with tan landau top). At the lower-right corner of this shot, a white Chevy Nova is parked at the corner (its vinyl top and trim has been poorly painted the same white as the body). Both these cars are repositioned to be at the roadblock location at the end of the chase, with the Nova slammed from behind by the truck and the Aspen parked near the cop cars. (00:07:00 - 00:07:40)
Deliberate mistake: Dr. Chandra returns to the Leonov at the end of the film with the device that Dr. Floyd designed to cut HAL's memory circuits. He hands the device back to Dr. Floyd, who tosses it in the air and catches it when it falls back into his hand. One problem - there was no gravity on the ship at the time. (01:44:00)
Deliberate mistake: When Betty walks away from the kissing booth it is clear that she has spike-like heels on her boots. When she steps on to the "moon" surface the spike heels are gone. Her spikes are on up to the point where they enter the room. I am pretty sure the crew did not want to puncture the bladder and have water all over the set. (01:07:25 - 01:09:35)