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.
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 RoboCop pulls out the assault cannon 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 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.
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 broken.
While rummaging through his old house, Murphy finds a partially burned photograph of his family, presumably from Halloween (as his son was dressed as a devil). During the flashback scene showing the origin of the photo from Murphy's point of view, he moved behind his son, who pointed his pitchfork at the camera. However, in the actual photograph, the pitchfork was pointed up and away from the camera.
The address listed for Murphy is 548 Primrose Lane. When Robocop arrives one the scene, the street sign says he's at the 3000 block of Primrose Lane. Additionally, when he approaches the actual house that's for sale, the number on the side indicates it's 3128.
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.
Robocop confronts Dick Jones at the top of the OCP tower. After Robocop fights off Directive 4 and Dick sends the ED-209 unit after him, Robocop escapes down three flights of stairs and is all the way down at the garage level.
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.
In the scene where Murphy is in the locker room and Frederickson's locker is being emptied, Murphy is seen placing his wedding ring on the top shelf of his locker. Shortly after when he is told to be front and centre by Reed, you can clearly see his wedding ring is back on as he loads his gun and closes his locker.
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.
When Robocop take his first night drive round the city, there is a wide shot from the back seat of his police cruiser, to the right of screen you can see the head and hair of the crew member in the passenger seat.
When Lewis fires the Cobra Assault Cannon during the final shootout at the foundry the muzzle flash and blast are so powerful that they knock the Lexan screen protecting the film crew and equipment off its mounting and into the shot.
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).
When Robocop is confronted in the OCP garage, the police commander issues a full assault against Robocop, and then elevates the assault by saying "Move in!". However, an experienced commander would not command his troops to open fire like that, particularly when the target is unarmed and showing no signs of aggression, due to the high risk of ricochets (from either the concrete or Robocop's armour) hitting police officers, .
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.
The Shell oil station where Murphy confronts Emil shows corrugated garden hoses spooled around a steel wheel as hose coming from the gasoline pump. No gas station in history has ever used such a setup, with spooled-up hose full of gasoline and exposed in the open, as it would be directly against several OSHA regulations regarding the dispensing of gasoline.
Most modern police stations have a sally port (a separate entrance for police vehicles only; a secure, controlled entryway to a fortification or prison) where they load and unload prisoners. In this case, this police station DOES have a sally port. Lewis (and later RoboCop with Clarence) should have brought their prisoners in through the sally port, not into the lobby where they could have posed a threat to civilians.
As Robocop leaves on his first deployment. An address is shown on his view screen. There is no 34th street and there is no Nash Ave. And while they didn't shoot this film in Detroit. They didn't even bother to use any Detroit street names.
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.
Dick Jones tells Clarence Boddicker during their meeting that there will be "two million workers living in trailers" to construct Delta City. Given that the population of Detroit was about one million people when the movie was made, it would be impossible for such a relatively small city to be able to suddenly support triple that population with all the space requirements for such trailers, in addition to water, sewer, garbage, electric, utility, transportation, food and other infrastructure needs.
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.
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 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.
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.
ED 209's right arm cannon wiring and barrel differ in color and shape/ alignment between shots in motion and steady-shots of ED during the board meeting.
This is obviously of the fact, that there were two different ED models used in this scene where one of them was 1:1 size and the other, a stop-motion miniature.
Robocop is obviously designed to be set in the future. One evidence of this is at the gas station where Emil confronts the clerk, the "college boy," and above the counter the gas station shows a sign advertising cigarettes for the then-outrageous price of $3.99 a pack, which was presumed to be a futuristic price. Yet, on the back wall behind the counter is an advertisement soliciting support for the 1988 Olympic athletes.
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.
Just before Boddicker's gang has its shooting spree on Murphy, they taunt 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.
Implausible police reaction times: Robocop enters the convenience store less than twenty seconds after the clerk presses the alarm. Later, at least twenty cops confront Robocop in the parking garage less than a minute after Jones calls for them.
When Emil opens fire on Robocop at the gas station, the explosion should have occurred as much as 27 seconds earlier than it did. While Emil is hopping on his motorcycle, one of his many rounds ruptures a fuel hose two feet away; creating a fountain of fuel spraying directly in front of him. Emil continues to fire two dozen more rounds, with all of the MAC-10s muzzle flashes making physical contact with the spraying fuel. Additionally, even though it is indeed Emil's lit cigarette that destroys the gas station (seconds after hitting the ground); it was first shown being tossed through the spraying fuel. In both cases, the gas station explosion would have occurred before Emil could start the bike and drive away.
The goof items below may give away important plot points.
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.
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 Robocop attempts to arrest Dick Jones, Jones confesses (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 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.
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 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.