When Murphy is brought to the emergency room the staff is heard checking for equal breath sounds well before the endotracheal tube is in place. Normally the breathing tube must be inserted before breath sounds are checked.
When we see the police officers on the shooting range, the person shooting in the last booth has his pistol held out straight, and continues to pull the trigger despite the fact that the slide is in the lock and safety position.
Various points in the chase at the beginning show a section of the Dallas skyline - notably Reunion Tower - which is both behind and in front of them simultaneously (they drive both toward it and away from it as between shots).
When RoboCop is shooting Dick Jones, Jones flies out of the second window from the wall on the interior shot, but when shown from the exterior of the building, Jones is flying out of the first window from the wall.
When Bob Morton gets off the elevator to go to the meeting, the elevator says "95th floor have a nice day" yet after the meeting when there walking back to the elevator it says 120th floor on the wall.
In the highway shoot-out/pursuit scene between Murphy and Clarence's crew, one of Clarence's men shoots the police car in the windshield and we can see holes in it. Then when we see the car from further, the windshield is perfectly intact. Then it goes back to being bullet ridden.
After the cops go on strike and Boddicker's gang tries out their new weapons by destroying nearby shops and vehicles, it is clearly night out. Within a few seconds of Boddicker next saying RoboCop is in the steel mill, they are hunting for Robo in daylight, which is alternately sunny and overcast between shots.
When RoboCop pulls out the assault rifle to destroy the ED-209 guarding OCP Tower, he fires two shots. After firing the second time, the camera cuts to ED-209 exploding. When it cuts back to RoboCop, there's a bullet casing lodged in the ejection port of the rifle which the prior view showed to be clear. For this to happen, he would have had to have fired a third shot.
When Murphy and Lewis are in pursuit of Boddicker and crew, Murphy asks for Lewis to give him her "piece." During the following akimbo style shooting, he's seen using a Sig P226 and a HK P9S. In the next scene, upon entering the steelwork both have Sig's.
During the first chase, as well as the windows mentioned above, the blue lenses of the light bar are shot out. When they move to the left (driver's side) of the van (right of screen), the light lens is back on and the strobes are flashing, But when they return to behind, the lights are again broke.
When Clarence goes to meet Dick Jones after being attacked at the Drug Factory, Clarence enters Jones' office and closes the doors, but the doors come open again; however, the next shot of Clarence shows the doors closed.
When Murphy and Lewis are chasing the Boddicker gang's van, Boddicker has Bobby thrown onto the police car, after which Lewis spins out, turns around and pursues again; yet, when they catch up to Boddicker's gang at the steel mill, the gang has already arrived, taken out the cash, and dispersed only a few seconds later.
In the scene where RoboCop and ED-209 are battling at OCP tower, ED-209 get's his left gun pod (which has 2 of the 20mm cannons) blown off. The right pod has a single gun barrel and the rocket launcher. When RoboCop takes the stairs down, and ED-209 follows, just prior to ED-209 falling there is a close up showing the right gun pod with 2 barrels and no rocket launcher.
When Clarence and his gang set-out for the final showdown with RoboCop, Leon slaps the roof of Clarence's 6000SUX. We can see the rear-view mirror fall off the windshield as the car is slapped, but in subsequent shots it is intact.
When RoboCop strikes the robber at the convenience store, it clearly shows RoboCop swinging his right arm backwards clothes-line style, dropping the robber to the floor, yet the robber is thrust forward into the glass case, which would have been impossible from that angle.
Just before Murphy gets his right hand shot off, his arm is beside his body with gunman Clarence standing on it; yet, when we see Murphy's hand being shot off, his hand is above his head, which is not possible with Clarence standing on it.
When RoboCop shoots the rapist in the crotch through the woman's legs, the shot is clearly into the woman's abdomen and not between her legs. Yet a moment later, the bullet hole is significantly lower on her skirt, at least a foot lower.
(at around 1h 10 mins) When Robocop attempts to arrest Dick Jones, Jones confessed (brags?) "I had to kill Bob Morton because he made a mistake. Now, it's time to erase that mistake." Robocop is on the floor and moving around quite a bit. and his head is turned 90° sideways. When Robocop plays the video in the conference room. It's an extreme close up of Jones, the shot is vertical and stationary, as though filmed in a studio.
When we first meet Joe, he has a beard. The second time we see him (the drugs bust scene) he has shaved it. But the third time (when Clarence and his men are hunting down RoboCop) he is fully bearded again, after a period of just a day or two.
When ED-209 is firing its rockets at RoboCop, the second time ED-209 targets RoboCop, there are three rockets in their launch tubes, instead of two. When the second rocket is fired, it launches from the correct tube.
When RoboCop first appears at the station house and gets set up in his cage, the man describing how he can be located to his exact location has a device with a fixed red LED in the center of it. Later in the Tower in Jones' office, the LED is now green and seen moving across the screen.
After RoboCop shoots out the tire of Emil's motorcycle as Emil flees the gas station robbery, the motorcycle slams into a parked car. A cable and pulley system is visible in front of the car's left front wheel, used to pull the motorcycle into the car. There are also "training wheels" visible at the rear of the motorcycle, to keep it upright as it is pulled toward impact.
When RoboCop is at the convenience store on his first patrol, he prevents the robber's shooting by bending the barrel of the gun. In reality, this would have been impossible because the robber was still holding the gun. To create that amount of stress so as to make the barrel bend like that while in the robber's hands, the robber would need to be as strong as RoboCop, otherwise the gun would sooner flip out of the robber's arms than bend.
When murdered cop Frank Frederickson's nameplate is removed from his locker in one of the opening scenes, it's spelled FREDERICKSON; however, when RoboCop later scrolls through the police computer looking at Boddicker's rap sheet and scrolls past Frederickson's murder, the name is spelled FREDERIKSON (with the C missing and the N off-screen).
The grenade used by Clarence to kill Bob Morton is a concussion style grenade, not a fragmentation (anti-personnel) type, neither of which is capable of producing the type of explosion that obliterated Morton's home. In order to achieve the orange and black smoke as shown, gasoline would have to be involved.
When RoboCop is first on patrol and responds to the convenience store robbery, the angle of impact with the suspect is inconsistent with the laws of physics. The suspect, after spending his rounds of ammunition, attempts to run past Murphy's left side, to which Murphy reacts by spinning around and clotheslining the suspect from the front, which would instantly send him to the ground; yet, in the next shot, the suspect flies face first into the beer cooler several feet away. In order for this to have occurred, Murphy would have had to spin around and strike the suspect from behind, not from front.
It would not be in line with RoboCop's programming to practice fire at the steel mill where Lewis was napping without first warning her. Instead, he just fires downrange of where she is, which is contradictory to all known firearm safety procedures.
Jones has a meeting with Boddicker and tells him Robocop must be killed, because Boddicker's confession was recorded and is admissible as evidence. Yet, Jones seems totally unconcerned about his own confession to Robocop about having Morton murdered, and having to "erase his mistake". Later on, Jones is in a state of shock when Robocop plays this recording back in the boardroom.
When RoboCop goes to the grocery store robbery and sends the robber through the glass door of the small refrigerator, you can see that the glass is already cracked and starts to break before the man goes through it.
After Clarence blows up the second 6000 SUX in the street with the assault cannon, he tells Leon, who's standing next to him, that RoboCop is in the steel mill and they have to go. When Leon shouts to the others to get ready to leave, he slams his hand down on top of Clarence's 6000 SUX and the interior rear view mirror falls off the windshield.
When RoboCop is first brought into the police station, one of the scientists shows a "device" that tracks RoboCop's location at all times. This is obviously supposed to be some kind of hand-held LCD screen showing a map and a marker; however, you can clearly see that the "device" is just a tiny printed map with an LED placed in the middle of it.
In spite of the erroneous floor indicator at OCP (the elevator said "95th floor" but the wall plaque said "120"), at the board meeting, we can clearly see outside that they are only about 300 feet up. If they were really on either the 95th floor or the comical 120th floor, they would be over a thousand feet up and from that height we wouldn't even see the ground from the meeting room.
When Bob Morton reveals RoboCop to the staff who are applauding him, RoboCop walks past a TV screen filming him, which shows him turn 90 degrees to his left, but in the POV shot he walks in a straight line.
Obvious blanks being fired during Murphy and Lewis's pursuit of Boddicker and co., Murphy is shown returning fire on the van's right side, intending to hit Boddicker, yet there are no bullet holes despite missing every shot on Boddicker's van's right side.
Just before Boddicker's gang has its shooting spree on Murphy, they taught him to turn around. Only Emil's lips move to voice his taunt. The taunts of the rest are heard while their lips are visibly too stretched in laughing to voice them.
When RoboCop is having his "nightmare", he thrusts his head backward several times, during which you can see the actor's neck between gaps in the neck-piece, rather than the pistons we see later in the movie (when he takes off his helmet).
When RoboCop attempts to arrest Dick Jones and struggles against Directive Four, his arm is at one point raised above his head, and you can see a circular hole in the rubber around his armpit, revealing a spandex jumpsuit underneath.
The goof items below may give away important plot points.
When Clarence Boddicker leaves a grenade to kill Bob Morton in his house, the timer on the bomb is inconsistent with the actual time of the explosion. In a shot showing Bob Morton struggling to grab it, we can see there's 3 seconds left on the timer, however 3 seconds later, it still hasn't gone off.
Dick Jones says "I had to kill Bob Morton because he made a mistake. Now it's time to erase that mistake." RoboCop records this and plays it back at the boardroom at the end of the movie. Dick Jones' vocal intonation is different in that recording from how it was when Jones originally said it.
When Lewis is pursuing Boddicker in the chase scene at the end of the film, Boddicker has a smashed windscreen; however, when he hits Emil with his car, the windscreen is intact. It then returns to being smashed.
When Clarence flips his 6000 SUX into the scrap pond, Anne arrives seconds later and the pool's surface is perfectly smooth, indicating that the car has been there long enough for all the waves to subside.