Continuity mistake: When Elliott gets food for himself and ET he takes the milk container from the top shelf of the fridge, and we see an empty space beside the Skippy peanut butter where the milk had been, but after Elliott drops everything onto the floor, in his next two closeups note the milk container (it has a distinctive curved design) is back on the shelf in the same spot beside the Skippy jar.
Revealing mistake: At the beginning, when people are walking through the metal detector and on the screen it shows them nude, the background is different on the screen. For example, the screen shows two people sitting down, but there are no people sitting down. (00:02:35)
Revealing mistake: Near the beginning of the film when Deckard and the other cop take off in the car to go to the police station, you can see the cables lifting the car up into the air. (00:10:05)
Continuity mistake: When the crew is outside and they're going to lock Blair in the tool shed, you can see someone nailing wood across the window on the front of the shed. The pieces of wood are horizontal. In the next shot (inside the shed), if you look at the window in the background, the strips of wood are vertical. When Mac goes back outside, the wood is horizontal again.
Continuity mistake: When Nicodemus is telling Mrs. Brisby that he looked at the words under the latch on the door and understood them, there is a clear, large label under the door. Then a different angle is shown and there is no label on any of the doors, but you should be able to see it still. (00:52:25)
Continuity mistake: In the training simulator at the beginning of the film, after Sulu and McCoy have both fallen, McCoy has his head resting on Sulu's hip at first. Then, in the next shot, his head is resting closer to Sulu's knee. (00:05:50)
Revealing mistake: When Alan gets up to go to see Dillinger, look at the cubicles. The first row that Alan came out of is real. In the immediate next row, the cubicle that is adjacent to Alan's has no visible exit, and the two that would be heading toward the white wall seem to be only leading to each other. The rest of the cubicles in the area are all a matte painting used to extend the set.