Continuity mistake: When the two Ninja robots fight, the robot on the left loses his head before the blade strikes.
Plot hole: The opaque red lined map that Otomo retrieves from his first fight is ridiculous. Why would people who know where the hidden base is be carrying around a map on them (which shows a route so basic that they'd have to be brain-dead not to be able to remember it anyway) just so that conveniently one of their enemies can get it?
Revealing mistake: When Robo gets his arm chopped off by Otomo, he stands up and in Robovision, you see that he needs power, but you cannot see Otomo who is supposedly right in front of him.
Other mistake: When Robocop is being repaired by the homeless guys, you can see clearly his stomach going up and down as he breathes. If he's mechanical he shouldn't be breathing, and even if they kept that bit of his innards, he's covered in a titanium shell so we shouldn't be able to see anything moving anyway.
Continuity mistake: When Otomo cuts off RoboCop's hand, RoboCop easily places his attachment in place of it and continues fighting. But his arm needed to be screwed off, and Otomo made a clean cut, so surely there would be bits of metal, plastic and wires that would have needed moving before RoboCop could put his attachment on?
Plot hole: When the elevator door sticks, he pushes the thick metal doors outward as though they were made of tinfoil. But when he reaches the room, he shoots out a silhouette in a flimsy wooden door to get in. How stupid. Total waste of ammunition and spoils the surprise factor.
Plot hole: What was the point of leaving the three men to guard the abandoned base? They would have stood no chance against any search patrol and would have simply given the Rehabs the map to the real base (on one of the three men). And why did the man even have that transparency with the red path, when he had no map to use it with? It was useless to him without a map, and only would have been a liability if he had been killed.
Continuity mistake: Why did RoboCop shoot a hole in the roof of the car at the beginning of the film? Sure it looks flashy and cool, but it is a car, and it has a door. There was nothing stopping him from opening the car door and shooting the Splatterpunks. It actually would have been quicker for him too.
Factual error: When Robocop flies through the window of the top floor of the OCP building, the Rehab leader's hair blows around. Being that high up, that is absolutely correct. But after the ninjas appear, there is no longer any wind and no one's hair moves. "Robocop 2" tells us that the OCP skyscraper is sixty stories high. There would be a constant "breeze" with the window busted open.
Factual error: When Robocop first flies into the the battle at the end of the movie, the whine from his jetpack causes the glass in some windows to blow outwards. Considering the sound waves are hitting the glass from the outside of the windows, they should be blown inwards not outwards.