Revealing mistake: In the shot where Dick Jones is falling from the top of the OCP building, both of his arms appear to be about a foot longer than they should be. (01:36:30)
Revealing mistake: 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. (00:11:55)
Revealing mistake: In the firing range scene, before Officer Lewis puts her gun down, and leans forward to look at Robocop shooting, we see him fire three shots. Look closely the second time he pulls the trigger. He pulls the trigger, but there is no ammo sound, nor is there a firing spark. This is in the VHS version. (00:32:10)
Revealing mistake: When they're supposedly tightening down the L.E.D. the scientist is using a normal drill bit attachment. (00:27:00)
Revealing mistake: As Emil is being washed out from the back of the truck by the toxic waste, it's obviously a stuntman. The stuntman appears to have a dark mohawk which does not match the actor's hair.
Revealing mistake: After Jones "introduces" ED-209 to Robocop, as he is descending the stairs, the top step can be seen through Robocop's head. This is because ED-209 is a stop-motion animation, and Robocop was matted into the scene.
Revealing mistake: In the closing scenes where Robocop pulls up outside the offices of OCP, he fires the rifle (in fact built around a slightly modified Barret Light 50 fifty caliber semi-auto rifle) at the ED209 across the roof of the car and destroys it. As he watches the robot and grins just before putting the rifle down, you can see he has what is known as a "stovepipe", in other words the last fifty caliber blank crimped shell fired has failed to eject fully and is stuck there poking out the side of the action just in front of his face (towards the left of the picture). The crimped end of the large brass case is easily seen. This is common with blanks in a gas operated semi auto which may not cycle the action fully - not the live ammo he's clearly meant to be using.
Revealing mistake: When Robocop is completed and they are going over his gear, they show a tracker that shows his location at all times. The tracking unit is obviously fake; the street layout is a decal and the "blip" that is Robocop is in a fixed position. (00:30:20)
Revealing mistake: When RoboCop is getting into his car after remembering about his former life, and breaking out of the police station, look at the bottom of the screen. You can see that Peter Weller is only wearing half of the RoboCop costume, his right leg comes into shot as he gets into the car. (00:46:40)
Revealing mistake: When RoboCop goes to arrest Dick Jones and starts to shut down, as he twists and turns we can see his real left arm in a black body suit under the costume.
Revealing mistake: When Robocop uses his thermal vision to see the hostages and gunman through the wall, you can see a long zipper in the back of all the thermal color pattern costumes they all wore to simulate thermography. This was most likely invisible to the eye in a dark theater but on an HD screen, it shows.
Revealing mistake: As Boddicker swings the bar at Murphy, as Murphy's head drops down while deflecting the bar, the skin make-up at the line where it meets the part covering the back of his head wrinkles up a moment.
Revealing mistake: When Bob gets killed by the main bad guy, his pants have unusual bulges in them, the blood packs.
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.
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