(at around 59 mins) Just before the car crashes into the police station, the officer at the desk is alerted to the car by the headlights flashing in his face, yet when we cut to the car, the lights are off.
(at around 47 mins) 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".
In some scenes, Reese has a clean shaven face. In others, he looks like he's growing a beard.
(at around 16 mins) 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.
(at around 37 mins) When the Terminator punches the windshield he shatters it completely, but in later scenes there is only a fist-sized hole in the windshield.
(at around 36 mins) As has been demonstrated on Brown Note (2005), and re-confirmed in Mythbusters Revisited (2005), Newton's Third Law establishes that bullets and shotgun blasts do not have the momentum to knock a human body backwards, although the trauma of being shot may cause them to fall backward. Since the Terminator is made of a solid alloy, is much heavier than a human, and cannot feel pain (confirmed by Reese), much less trauma, it should not react at all to being shot, much less be thrown backwards by the shotgun blasts in Tech Noir.
(at around 8 mins) May 12th in 1984 was a Saturday not a Thursday. (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.)
Thousands of rounds are fired by various automatic weapons and shotguns throughout the movie, yet none of them ejects any empty shell casings when they're being fired.
(at around 1h) Even with a taped-together pair of large-capacity magazines, there are far too many shots fired from the Terminator's machine gun at the police station.
(at around 17 mins) Reese starts the car by twisting the starter wires together; this is incorrect. The "run" wires (these get connected when the key is in the "run" position to allow the spark plugs to fire; they get disconnected and stop the engine when the key is turned off) get twisted together, but the starter wires are just temporarily held together till the engine is cranked and started; they are not connected continuously to keep the engine running.
(at around 33 mins) 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.
(at around 14 mins) During the gun shop scene, the Terminator asks the clerk for a 'phased plasma rifle', presumably a weapon from its own time (2029). Some claim that the Terminator, as an advanced infiltration unit, should have had detailed files on the current time period. Therefore it should have known that the plasma rifle did not exist yet in 1984. However, as Reese explained, most of the records were destroyed during the war. Skynet knew very little about Sarah Connor, apart from her name and city in 1984. It therefore doesn't seem unlikely that the information on weapons availability in the 20th century had been lost as well. The 'phased plasma rifle' may have been an earlier version of the energy weapons seen in 2029, something that might have existed in the late 20th century, so the Terminator just tried if it was available.
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.
(at around 1h 1 min) Cutting the power in the electrical box would not cause the florescent lights to come apart and explode; they would just go dark. The Terminator doesn't cut the power - he actually surges the lights with the wire from the high-voltage box. A high voltage surge like that could definitely cause fluorescent lights to explode, if they got hot enough.
(at around 1h 2 mins) When Kyle rescues Sarah (during the police station massacre), he screams "Sarah!" loud enough for anyone nearby to hear it. This somehow does not draw the attention of the Terminator himself, allowing Reese and Sarah to make their escape. However, the audience is never shown exactly how large the police precinct is, so the Terminator could be sufficiently far enough away to not hear Reese yelling over the sound of all the gunfire.
At one point during Reese's explanation, Sarah begins to say "Ky..." and then stops herself. Linda Hamilton obviously forgot that Sarah doesn't ask Reese's first name until much later.
(at around 59 mins) When the Terminator talks to the desk officer, you can see through the glasses which shows both his eyes intact, even though one should be missing.
[00:32:00] When the Terminator is shooting Ginger, he can clearly be seen closing his eyes with each shot. The flash of the gun should not affect the Terminator.
(at around 1h 12 mins) 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).
(at around 1h) When the Terminator drives the car into the police station, the desk sergeant who gets crushed is obviously a dummy.
After the Terminator says "I'll be back" and leaves the police station, the desk officer is shown filling out and signing an official police report with a pencil. Reports would instead be filled out with a pen to prevent altering and falsifying them.
When Reese hides in the department store from the cops, he steals a pair of sneakers, but doesn't grab some socks, too.. on top of that, he chooses to keep wearing the disgusting pants that he stole from the homeless man instead of taking something new and fresh.
When the cops are searching for Reese in the department store, they just wave their flashlights around a couple of times, then easily give up instead of "spreading out" in a special search pattern.
(at around 1h) Just before the Terminator kills the power to the police station, he comes to a door at the end of a hallway. He fires his shotgun, but we hear the sound of the machine gun instead.
(at around 24 mins) When Sarah is walking from her apartment you can hear the heels of her shoes hitting the pavement. Later when she's walking into the disco she's wearing tennis shoes.
(at around 4 mins) At the beginning of the film, the garbage truck driver's mumblings are completely mismatched from his lip movements.
In the police station shoot out, when Lance Henriksen's character, Vukovich, shoots The Terminator in the back with an automatic rifle, the sound the gunfire happens before any muzzle flash is seen.
(at around 1h 30 mins) Sound synchronization wrong when Kyle and Sarah are getting up to escape from the Terminator robot, arising from the flames Sarah's s are not matching her mouth actions.
(at around 1h 30 mins) When the Terminator finishes punching the hole in the door to the computer factory and walks in, a puppeteer's head can be briefly seen behind him.
(at around 36 mins) When the Terminator is rising to his feet after getting blasted out the window, a production vehicle and a huge stage light are visible behind him.
(at around 1h 1 min) As Vukovich is rushing toward the auto-weapons storage room, the camera light is briefly visible on his back.
(at around 5 mins) As the Terminator walks toward the wall at the Griffith Park observatory, the shadow of the camera can be seen on the far left of the screen before the shot ends.
In the future scene where Reese and other fighters are just entering the underground 'base', you can see a camera crew off to the left as the scene pans out.
The Tech Noir club is on West Pico Blvd. At around 38 mins Kyle and Sarah Connor leave through the back door and get into Kyle's stolen car, pursued by the terminator. They back down the alley, emerge onto a street and hit a car. A policeman calls it in, stating that the incident took place at 7th and Broadway. This intersection is six blocks (3/4 of a mile) away from Pico. It is quite conceivable that the club could have been within a block of 7th and Broadway, but not on Pico. Clearly the distance has been compressed, and in such a way as to be in conflict with the story.
Traxler allows Sarah to take a nap on the couch, and he tells Sarah her mother should arrive from Big Bear in about an hour. Shortly after, the Terminator arrives, and Sarah and Reese flee, all of this happening at night. Later, the car Sarah and Reese take runs out of gas, and they spend the night under a bridge. A short time later, it's light out, or the next day, and they make their way to the Tiki Motel. Sarah then gets on the phone, and we find out the Terminator is there, and has killed her mother, mimicking her to get Sarah to reveal her location. The question is, why would Sarah's mother still be at the cabin in Big Bear when she was supposedly on her way to pick up Sarah at the police station? No mention is made of her stopping along the way at a pay phone to call her, and there were no cell phones in 1984. It also takes a lot longer than an hour to get to get to Los Angeles from Big Bear. The Central Division of the LAPD is about 120 miles (190Km) from Big Bear, with the first 40 miles (65Km) which is on highway 38, a twisty two lane mountain road. It's closer to a 3 hour drive in all.
[1:29:00] 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.
It's unclear why the police were chasing Kyle Reese right after he arrived, or how they got there so quickly, especially in Los Angeles where the per-capita of police is roughly ½ the national average.
Terminators are designed as infiltration units. Creating them with the physique of a hulking bodybuilder, with a unique accent, is quite counter-productive. They don't need extra size muscles, being androids with superhuman strength anyway.
(at around 1h 3 mins) Reese and Sarah ditch an AMC Gremlin after the police station massacre, and they then sleep under a bridge nearby. Despite possibly being exhausted, it seems like they're leaving themselves open to attack by the terminator by leaving the car in the nearby woods, then sleeping near it. The terminator could certainly have decided to travel down the same road they did, and possibly have found them.
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.
(at around 53 mins) When 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.
(at around 1h 18 mins) Kyle would not have told Sarah to screw the end cap onto the pipe bomb till he had the fuses ready, since he would have to insert the fuse in through the cap and into the explosive paste.
After he has stolen the cop's pistol and hidden inside the dept. store, the police search for Reese using only flashlights. An fleeing armed fugitive with a stolen cop's gun should have warranted at a minimum drawn pistols from the police.
(at around 15 mins) 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.