Deliberate mistake: When the board member is shot up in the beginning by ED-209, in one or two shots you can see the bullet impacts happen about 1/2 a second after the shot starts (Criterion DVD version).
Visible crew/equipment: When Clarence Boddicker (Kurtwood Smith) is killed by Murphy (Peter Weller), Boddicker falls into the steel mill's water, blood spewing from his neck. Sharp eyes are required here to see that there is someone standing against the wall in the background...
Visible crew/equipment: When ED-209 is being demonstrated for the first time and goes out of control, when the young executive is being shot, repeatedly, by ED-209, you can see packets of red paint strapped to his back, under his suit.
Continuity mistake: When Murphy and Lewis are chasing the villains in the beginning, one of the bad guys shoots the windshield of the cop car, leaving a hole and messing up the glass. Not even a second later, the windshield is fine.
Continuity mistake: When Robocop is fighting Clarence Boddicker in the cocaine factory he throws Boddicker through a plate glass window. If you watch closely, you can see the window shatter about 1-2 seconds before he goes through it.
Factual error: After Robocop stops the criminal from robbing the convenience store by bending his machine gun, the robber tries to run past him, only to get clotheslined by Robocop. The direction the robber flies after getting hit defies all physics.
Visible crew/equipment: Robocop tries to arrest Dick Jones but fails, and an ED-209 is brought in to destroy Robocop. During their fight scene, it fires a missile at Robocop, and you can clearly see the guide-wire that the missiles fly along (especially in slo-mo).
Continuity mistake: When Robocop looks up his old address, his house number is the 500's on Primrose Street, but when he drives by the sign on his street it says he is in the 3000's section.
Continuity mistake: Just before Clarence Boddicker crashes his 6000 SUX into the water after colliding with Lewis' Taurus Cruiser, there is a scene where his car is charging toward the camera, and a hubcap comes off and whistles past the camera, in fact they even put in a sound effect. But in one of the next shots, the hubcaps are back on.
Visible crew/equipment: When Clarence is racing away from Lewis near the end of the movie, the camera zooms in on Clarence driving the car and the camera men and camera truck are visible in the reflection of the car.
Visible crew/equipment: In the scene where all the OCP executives are listening to Dick Jones presenting ED-209, and while the "old man" starts talking about Delta City, watch when the camera moves along backwards to show the city model he's talking about and you can see reflected on several TV sets that are on the wall both the camera operator and another man behind him, perhaps the boom operator.
Revealing mistake: After the one bad guy crashes into the giant vat of Toxic Waste, hardly any of the liquid from the container spills out for the first two shots. Then a few cuts later, almost all of it pours from the back of the truck. Judging by the size of the hole it left, more liquid should have been coming out around the truck, not just through it.
Continuity mistake: When Clarence is talking with the other drug dealer in the warehouse, tempers flare and guns are drawn. The Asian gang member racks his shotgun (thus loading the weapon). Wouldn't he have kept it loaded? Anyway a few seconds later Robocop enters and the same Asian guy racks his shotgun again and no shell is ejected.
Continuity mistake: When the ED-209 gets to the stairs and tries to give the first step, its right arm changes from having one cannon and missile launcher to having two cannons and two ammo clips of sorts (just like its left arm). When ED slides and is falling, the arm changes back to normal; and at the end of the fall, its arm has two cannons again.
Continuity mistake: When Robocop shoots Dick Jones, the bullets go through Jones but not through the window which is right behind him.
Continuity mistake: When Clarence's car is flipped over at the steel mill, he gets out and starts firing at Lewis. Look at the windshield on Lewis's car. It's in perfect condition and all of a sudden 9 bullet holes appear in it. Clarence didn't even shoot his gun that many times.
Continuity mistake: When Bob Morton, Johnson, and Kinney get off the elevator, a computer voice chimes that it's floor 95. After the board meeting, Morton and Johnson leave the board room (and it's the same floor as you can see the two paintings on the wall that lead to the board room) a sign next to the elevator says "120."
Continuity mistake: When the bearded man is robbing the convenience store, he demands that the owner opens the safe. Look at the Lite cans on the safe. When seen from the right, there are four cans. When the owner kneels down to try and open it, there are now three. When we cut back to a view from the right there are again four. Finally when the robber is shooting at Robocop there are only two.