Continuity mistake: In the scene were Johnny is fighting Robbie, his belt breaks, and is hanging down. Next shot it is fastened again. And then it is hanging down again. (01:11:45)
Revealing mistake: When Robocop is completed and they are going over his gear, they show a tracker that shows his location at all times. The tracking unit is obviously fake; the street layout is a decal and the "blip" that is Robocop is in a fixed position. (00:30:20)
Continuity mistake: When Owen arrives at the hotel to meet Neal and Del to drive them to the train station, Owen is wearing gloves on both hands. As he introduces himself and shakes their hands, Owen's right hand is now bare even though there wasn't enough time to remove the glove. (00:33:55)
Continuity mistake: When the tanks are moving into the city with the Marines i.e. after meeting Private Cowboy, Animal Mother and the rest, they run into a firefight. When they stop shooting and are reloading watch the leader's ammo clip. It's missing in one shot of him, in the next he's ejecting the magazine and putting in a fresh one before shooting the two Vietnamese with it.
Factual error: When they are driving back home from the holiday cottage you can clearly see an M25 sign in the background. The M25 didn't exist in the 60s.
Visible crew/equipment: Loretta calls for Ronny at the bakery, and when he picks up the phone then promptly hangs up on her, the dark protruding outline of the microphone wire is visible at his right side. It happens again when Loretta visits the bakery and Ronny tells her Johnny took his life from him. Additionally, later when Ronny and Loretta spot each other at the fountain in the Lincoln Center Plaza, there appears to be an actor's mark at Ronny's feet. (00:25:00 - 00:27:05)
Continuity mistake: During the scene where Ness kills the Italian mobster in the lodge near the border, the moment he shoots him the wooden rail behind has two sticks underneath, half a second later, when the mobster is flying backwards dead, the sticks disappear, and a second afterwards, when he is laying dead, the rail's appearance has nothing to do with the previous two.
Continuity mistake: In the club changing rooms Gekko fiddles with the knot of his tie but does not neatly fold his shirt collar, which exposes the tie at the back. When he puts on his jacket the collar and tie now appear properly dressed. (00:28:00)
Other mistake: After Dan visits his wife in the hospital, he goes to Alex's apartment. In the scene where he's chasing Alex and crashes into the glass door, shattering it, look closely at his face and you'll see it's not Michael Douglas but a stunt double. A few seconds later when they are struggling in the kitchen, look again and you'll see the same stunt double.
Revealing mistake: When Paul Kersey blows up the restaurant, there are obvious dummies in the booth. (00:46:01)
Continuity mistake: When Molly Ringwald is on the phone at the club and gets approached by the girl in orange, throughout the whole conversation the position of the phone receiver in Randy's hand is wildly inconsistent. (00:09:30 - 00:11:00)