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.
Trivia: At least two of the characters in RoboCop 3 are based on Frank Miller's, (the film's screenwriter), own comic-book creations. 'Otomo' the cyborg samurai, pays homage to his "Ronin" comic about a masterless samurai whose spirit is reanimated with futuristic biotechnology. 'Bertha Washington', CCH Pounder's freedom fighter in the film, is a reference to Martha Washington, the freedom fighter from Miller's "Give Me Liberty."