Factual error: One of the brain surgeons says about Cain's brain, "it's nice and clean in here, there's no damage", except we see throughout the film Cain using the drug Nuke, even a new variation of it called Blue Velvet. When he injects it he's with his chemist Frank, and mentions two of its ingredients, "benzadrine and scopolamine" - no way his brain would be nice and clean.
Continuity mistake: When RoboCop is being scraped up against the wall creating a shower of sparks, we cut to views of Cain. In one of these shots of Cain, the background suddenly changes - the wall he's scraping up against is nowhere to be seen and the sparks vanish. In the other shots of Cain, the background is correct. For some reason, a shot was taken from another part in the sequence and added in here, creating an odd continuity gaffe in the background. (01:02:02)