Before the TechNoir scene, Reese pumps his shotgun at least twice, which would load a shell into the chamber and make it ready to fire. But when he identifies the Terminator at the nightclub, he has to pump the gun again before firing.
During the scene where the psychologist is talking to Reese, the attending police officer in the interrogation room has his sidearm on his hip. Police officers don't wear their sidearms when in an interrogation room with a suspect.
When Det. Vukovich laughs at Dr. Silberman's ray gun joke, he can be seen reacting to an off-screen crew member who must be gesturing for him to stop looking at Sarah Connor and back to the video monitor.
When the Terminator tosses the bearded man away from the phone booth and begins searching the phone book for Sarah Conner, he uses his finger sliding down the page to assist separating the lines of type, the way human beings do when they read. Yet the Terminators have specially enhanced telescopic vision that allows them to zoom in/out, etc., on anything, even in the dark. It therefore makes no sense that this Terminator would have to use his finger to assist with his reading, he should be able to merely glance at the book and zoom in on the entire page, or on the smallest part of the page and process this information in seconds.
When the Terminator is stalking Kyle and Sarah in his police car, the sticker on the driver's door reads "To care and protect". When the car is later wrecked in a tunnel, the sticker has changed to "Dedicated to serve".
When Reese tosses the third pipe bomb, we can see that the pick-up and motorcycle are almost at the end of the tunnel. But when Reese tosses the fourth bomb, the two vehicles still have a long way to go. After the fourth bomb explodes, the truck and motorcycle have cleared the tunnel.
When the Terminator kills the first Sarah Connor, he comes through the door and extends his gun arm fully. After a brief cutaway he fires, but he is now behind the door frame and his arm is in a different position.
When the Terminator gets into the tanker truck, there is a close-up shot of his left hand grabbing onto the type of door handle that protrudes from the door, and pushing the button on the handle with his thumb. But when the Terminator is chasing Sarah and Kyle with the truck, the door handle is the rectangular type that is recessed into the bottom right corner of the door.
When Reese starts his explanation in the Ford LTD, he appears to have a brand new wound under his lower lip. When he continues his explanation in the other car (which is only a few minutes later) the wound has been healed and replaced by a scar.
When Sarah tries to escape from Reese in the first car chase, he grabs her by the hair. His grip on her (grabbing her hair, pinning her to the seat with his arm, shoving her head to the floor, or not holding her at all) changes frequently during the chase.
In the parking garage, when Reese and Sarah get into the car to steal it, Reese's coat gets caught in the door of the car and is pulled tight enough to restrict his movement. A moment later, the coat is free and loose around his neck.
As Kyle and Sarah are sneaking toward another car in the parking garage, a police car with the serial number 1874 drives by. The number 1874 is also visible on the Terminator's police car. The first car that drove by couldn't have been the Terminator's because a second cop is visible in the passenger seat.
When Sarah is first holding the iguana, she is holding it across her body, the shot then switches to a head-on and the iguana is resting on her shoulder. It then switches back to it's original position.
After the Terminator finishes operating on himself and puts on the sunglasses, he only has a shirt on, but when he walks towards his bed to get the guns from underneath the mattress, he is suddenly wearing a leather jacket.
The number 14239 appears above the front door of the first Sarah Connor (a similar number 14329 appears above the entrance of the Alamo Gun Shop) but does not match any of the addresses for Sarah Connor shown in the telephone directory.
In the TechNoir scene, when Sarah Conner sits down, there is no Canada Dry drink in hand. Seconds later, during the same "You've got me Burning" song that is playing in the disco, the bottle is in hand.
Just before the Terminator crashes his car through the police station door, the officer is writing on a form with his left hand on the table. In the next cut he has his left hand on the form. The position of the pencil also changes in the two shots.
When Traxler and Vukovich arm up with assault rifles during the police station massacre, an officer with a shoulder rig is seen behind them grabbing his own M16. Later, when the station is on fire, the Terminator steps over the same officer dead on the floor, armed with only his revolver.
When the tanker truck runs over the Terminator and comes to a stop, the driver gets out to check on him while the passenger waits in the cab. The driver however doesn't close his door and the door fails do so on its own. After the Terminator kills the driver, he opens the door and commandeers the truck. Who closed the door? There's no reason for the passenger to have done it.
In the Tech Noir club, the Terminator passes by a woman on the dance floor wearing an orange shirt. A few shots later, when the Terminator focuses on Sarah, the same woman can be seen in the background sitting at a table and talking with friends. There wasn't enough time for her to move.
May 19th in 1984 was a Saturday not a Friday. (This error was due to the script of the film being written in 1983, and the film itself was to begin production that same year, but ultimately was postponed because of Arnold Schwarzenegger's commitment to finishing another project at the time. When it was decided to have the film set in 1984, the writers chose not to change the day of the week.)
The Terminator purchases firearms at a gun store, including a short-barreled, automatic Uzi. There are strict federal laws, and California has had bans on these for decades. No gun store sells them, and no criminal enterprise would have them readily visible on the wall. Converting a long barreled semiautomatic Uzi to full auto takes completely different internal parts, a machine shop and precise tooling.
The three "Sarah Connors" are listed in different sections in the phone book when Reese, The Terminator and Sarah Connor look them up (right page, left page, right page). They might have been different editions, though books at pay phones are generally all replaced at the same time.
After Reese and Sarah Connor flee the police station, Reese is bleeding from a bullet fired by the Terminator. While the car's windows were not broken during the gunfight, the driver's window is either rolled down or missing, and he could easily have been hit through it - or indeed he may even have been hit by a stray bullet while making his way through the police station, which, throughout the Terminator's attack, is riddled with gunfire.
When Sarah is in the night club she has to put change into the pay phone to call 911. While 911 calls are free, many pay phones in the 1980s required you to insert a coin in order to obtain a dial tone.
During the police station massacre, the camera is positioned on the floor, and shows the Terminator shooting through a door on the left. As he fires his gun, the supposedly dead cop in the foreground can be seen to jump.
During the flashback scene in which a Terminator infiltrates the underground human hiding place and starts killing people, if you look at the right side (his right side) of the Terminator's face by his eyes, you can see a flat line which is part of the makeup used to give him his glowing red eyes (like the sunglasses with LED lights that were popular to wear in the 1980's).
While assembling the pipe bombs, Kyle tells Sarah to be very careful, since the explosive used is very sensitive. Yet after all the bombs are assembled, Kyle hastily throws them into a zipper bag. This action would certainly have detonated real bombs of such sensitivity.
During the police station massacre, just before the Terminator shorts out the lights, he shoots a policeman in the back. The policeman is clearly seen smiling just before he starts to flee from the Terminator.
When the Terminator gets on the motorcycle to chase after Sarah in the pick-up, he turns on the ignition key and jumps up on his right leg to kick start the bike, but you hear a electric starter motor instead before he rides off.
When Sarah and the Terminator are crawling through the hydraulic press, the top of the press can be clearly be seen wobbling like plywood in the background lighting. This is the same press that is strong enough to crush the robot by the end of the scene.
After Kyle appears in an alley after traveling through time, he steals a pair of pants from a wino in the alley. Kyle has a slim, athletic figure, and the wino is a large man with a big waistline. Yet the pants fit Kyle perfectly.
When the Terminator is done operating on his own eye, he has a robotic eye. As soon as he puts his sunglasses on, Arnolds eyes are back to normal and clearly visible through the glasses from that moment on.
The message on Sarah's answering machine goes, "Hi there... Ha-ha, fooled ya. You're talking to a machine..." with a pause between "Hi there" and "Ha-ha". When the Terminator has shot Ginger, the answering machine starts and we hear the words immediately following each other. Also, when the police call Sarah's apartment, the message changes/speeds up; it is much quicker.
We see Ginger walking back to the bedroom with a plate of food and a glass of milk. When Matt crashes through the door, Ginger tosses and drops the food. When Ginger is shot and is trying to crawl away from the Terminator, the food on the floor in the hallway had some how disappeared.
When Kyle and Sarah hit the Terminator with their truck at the Tiki Motel, the grill has significant damage. During the highway chase, the shots of the front of the truck show no damage to the grill whatsoever.
The events from the time Sarah and Reese arrive at the hotel until the love scene are all during the day. In the middle of this Sarah calls her mom's cabin and talks to the terminator. The shot of the cabin is at night, as is the following shot of the terminator riding his motorcycle. Then everything is daytime again until he arrives at the hotel.
The phone number that Sarah Connor gives the Terminator (impersonating her mother) for the Tiki Motel, where she and Kyle are staying, is 408-555-1439. However, after the Terminator hangs up with Sarah, we see him dial 555-1639 and get an answer from the Tiki Motel.
When the Terminator skeleton rises out of the flames, a silhouette of a crew member can be seen behind the flames, rising from a crouch to pull a big lever. As the lever comes down, the metal skeleton rises up.
When the Terminator stumbles out of the burning cab, he collapses and burns in the fire. Its skull is clearly shown burning with no internal machinery. Later, when it rises out of the fire, it does so from underneath wreckage of the cab. These two inconsistencies have led some to erroneously believe that there was someone else in the truck.