Continuity mistake: In the exterior front shots of Elliott's house there are some significant changes to the landscape in different shots. For instance, the two lampposts at the bottom of the driveway change to an entirely different style in some shots, and the huge garden boulders repeatedly vanish and reappear. Also, note when Michael takes off on Elliott's bike to go search for ET, the in-ground lamppost that should be beside the mailbox has vanished, but it reappears when all the government agents are setting things up outside the house.
Other mistake: When Deckard visits the Tyrell Corporation, he prepares to test Rachel with the "VK" machine. He is shown putting his briefcase of the table and lifting the "VK" machine out and onto the table. If you look closely, the "VK" machine is already on the table and Harrison Ford is miming the lifting - there is nothing in his hands! (00:19:45)
Continuity mistake: As Gant is pulling the Firefox out of the hangar, it is still very dark, as in pre-dawn. But as the Russian officers are shown shooting and watching the Firefox take off, it is suddenly much lighter outside as if it is after dawn and the sun can even be seen. But it would have taken 30-60 minutes for the light level to change that much.
Continuity mistake: The sequence in which Dragon is chasing Mrs. Brisby through the field, up the tree and eventually into the mill's lake, watch his eyes. The original placement is (from viewer's perspective) blue on the right and gold on the left. When he chases her up the tree the gold one is visible on the right, it then switches back when the camera cuts back to a wide shot. This happens again a few seconds later near the lake.
Continuity mistake: When the Swamp thing goes to destroy one of the trucks chasing Cable, the trucks used are chevy blazers but the one he wrecks is a International scout.
Visible crew/equipment: When Alan and Lora go to see Kevin Flynn at his game room they find him playing his videogame 'Space Paranoids'. After he finishes playing, he turns around to talk with Alan and Lora. As they are speaking you can see the microphone coming up from the bottom of the screen. It even hits Kevin Flynn in the hand.
Continuity mistake: When Trash shoots the bounty hunter with the grappling hook, he shoots it at his stomach. After he ties it to the bike and drives off dragging the bounty hunter, the hook is now in his back.
Visible crew/equipment: In the scene where the staff member is cleaning up the research room with the animal cadavers there's a top-down shot of him at the communication panel. Directly in front of him there's a microphone visible that seems to be held by a filming crew member, as it moves out of sight after some seconds. (00:15:35)