Revealing mistake: When Robocop throws the robber through the food machine, just before he hits the glass, it is break away and almost looks as if it is already broken.
Continuity mistake: When Reed is going to Fredrickson's locker, his left hand is going to the handle. In the next shot, as he is taking the nameplate off, you see his fingers of the left hand by the nameplate.
Continuity mistake: The final fight scene at the ruined industry area starts in darkness, but ends at daylight, switching several times.
Continuity mistake: At the shooting range, the bullet holes on Murphy's cardboard target differ between the front and back shots.
Continuity mistake: After the ED-209 kills the business man, the blood on the city scale model disappears. (00:12:00)
Other mistake: Just after Dick is fired, Robocop shoots him. Robocop shoots Dick twice and we see two exit wounds on Dick's back. Robocop fires a third time, and two more exit wounds appear simultaneously lower down. (01:35:50)
Continuity mistake: When Dick Jones goes to see the head of OCP, he leaves the door ajar. However, later in the scene it is closed. Neither of the men in the room goes near it.
Continuity mistake: The first time Murphy is chasing the criminal van, the headlights on the police Taurus change from double round to single square (stock) repeatedly throughout the scene.
Continuity mistake: In the scene where Lewis is hit by the black guy at the steel mill, her body changes direction when she falls.
Continuity mistake: The first day together, Murphy and Lewis are in the car exiting the police station. When the angle changes to a back view of the car, Lewis is gone. (00:06:30)
Answer: When Bob Morton is told by a tech that one of Murphy's arm was saved, Bob stated that he wants total body prosthesis. Meaning Robocop's entire body was synthetic. None of his actual body was used. The only thing that was used was Murphy's actual face.
Also, his human brain, and possibly his spine, where OCP could wire him into the suit.
Movie Nut