In the shot where the T-1000 drives the truck off the street and into the canal to chase John Connor, the axle breaks down completely when hitting the ground. In the next shot the truck is stable again.
The Terminator jumps his Harley off a ledge down into a ravine. In the first shot of the jump, the ledge he jumps from is pointed. In the next shot, it's flat.
The T1000 fires rounds into the Terminator's back, but the damage to its jacket disappears when he is thrown through the window. Director James Cameron said the scripting of this sequence at the time of filming was different.
When the Terminator's arm gets caught in the gears, he severs it below the elbow to escape and continue fighting the T-1000. Towards the end of the fight, when the Terminator is crawling towards the grenade launcher, the damage is well above the elbow.
When John, Sarah and Terminator take the police car during the escape from the mental clinic, the number on the plate changes in the following shots from 999273 -> 999232 -> 999273 -> 999001 -> 999013 -> 999018.
When the Terminator uses the M79 "Thumper" Grenade Launcher to blast open a door at Cyberdyne he is only standing about 10 ft away from the door and it explodes magnificently. This is impossible as the 40mm HE (High Explosive) rounds fired from this weapon do not arm themselves until they have traveled 30 meters (approx 90 feet). So the round would have simply dented the door or punched a 40mm size hole in it depending on the material the door was made of.
Dyson has to go through what is supposed to be a "clean room" to get to the storage area for the chip and robotic arm. Clean rooms are not used as access routes. Nobody would be allowed to enter the room without proper gear, like the two workers are wearing. They are meant to protect either the workers from hazardous substances, or protect whatever they're working on from contamination. So "civilians" wouldn't be allowed to simply walk through.
After the T-1000 crashes the tow truck into the canal bridge, we see fuel leaking and a battery cable swinging in the wreckage. The sparking cable is shown to ignite the fuel causing the truck to explode. The tow truck runs on diesel, and diesel wouldn't explode like this.
In their escape from Cyberdyne, Sarah and John are passing one gas mask back and forth. Even if this might have enabled one of them to carry on (doubtful, especially since every time they switch it carries the tear gas inside to the new user)), in their final dash it is John who is wearing it, and yet Sarah is using her eyes to guide both of them to safety through the clouds of tear gas. At best, she would have had to keep it on and make him close his eyes and hold his breath.
The SWAT team burst into the room at Cyberdyne and shoot without hesitation. This would be an illegal tactic, as for all they know John Connor and Miles Dyson were being held hostage by the Terminator and Sarah Connor. The SWAT team also end up shooting and killing Miles Dyson who wasn't holding any visible weapons and wasn't posing a threat to anyone.
(at around 1h 40 mins) When the T-1000 is in the helicopter chasing Sarah, John and T-800, he re-loads his gun. He uses both of his hands to re-load, and there is a third hand clearly visible controlling the joy stick for the helicopter. He simply grew an extra arm to fly the helicopter. In fact, he has four arms in the scene, all of which are clearly focused on in shot.
When the T-1000 arrives from the future and steals a police car, he pulls up John Connor's information on the police computer including his home address. Yet inexplicably, the T-1000 doesn't show up there until the next day, after the T-800 had already come and gone. However it may be simply that the T-1000 is further away from Connor's home than the T-800, the John Connor of the future knowing where he used to live and ensuring the T-800 materialised nearby.
(at around 1h 15 mins) At the playground, when Sarah desperately tries to warn people, the shockwave blasts everything (even the charred flesh from the bones) but the little horse on a spring in the background doesn't move at all. Since this is a dream sequence, it doesn't have to obey the laws of nature.
(at around 47 mins) The T-1000 is not supposed to be able to turn itself into moving parts of any kind. But when it kills and replaces the hospital security guard, it has many moving parts before it takes the guard's gun - a keyring full of keys, a nametag with a clip, etc. However, these items are simply mimicked by the T-1000 and are not actually complex objects with moving parts.
(at around 1h 12 mins) Dogs bark wildly when a Terminator is near; yet, at Enrique's ranch, there are dogs playing despite the Terminator being close by. However, in the first movie Reese simply says that the Resistance used dogs "to spot Terminators." He doesn't say that all dogs bark at all Terminators. Dogs are individuals, and one may bark at an intruder while another may not.
After the Terminator's mechanical arm is freed from the cog, his real arm covered with a black sock is visible under his leather jacket. The outline of a wrist watch under the sock is also visible.
Steam throttles are clearly visible when the Terminator throws the biker onto the stove.
John Connor grows visibly taller even though the movie takes place over two days (see also trivia)
The Terminator stabs a biker in the shoulder causing the biker to be stuck to the pool table. The knife is not long enough to go through the biker's shoulder and still stick him to the table enough that he would not be able to move at all.
Obvious stunt double for Edward Furlong riding the motor bike during the chase scene in the drain. It is obvious it is an adult and not 12 year old Furlong.
When the T-1000 accesses the police computer at the beginning of the movie, we see that John Connor was born February 28, 1985 and is currently 10 years old. This would set the film between 2/28/95 and 2.27/96. However, the terminator says Judgment Day took place on August 29th, 1997, referring to it as being three years in the future. The terminator also says that judgment day would be three years in the future. As August 29th is specifically stated, this would place judgment day in the summer of 1998, not 1997.
T-1000's pistol often sounds suppressed as it fires, despite no suppressor being attached to the barrel.
In the first movie, because there was more than one Sarah Connor in the city the Terminator had to kill each one. In this sequel, the T-1000 typed John Connor's name into the police cruiser's computer and it returned only one result. As common as the names "John" and "Connor" are, there would certainly be more than one.
It is implausible that a trio of wanted fugitives-who commandeered and destroyed a building and several police cars, shot at and injured multiple police officers, and were suspected of carrying out a massacre of policemen at a precinct years earlier and were wanted by the authorities-would not have police reinforcements pursue them after leaving the Cyberdyne site. This is further made more implausible by the fact that the emergency evacuation of the steel mill was an easy tip off to the authorities as to where the fugitives now were.
The liquid nitrogen truck drags across the road for much longer than its momentum would realistically allow.
After Sarah beats up the creepy guard at the mental hospital and is running down the hall with the nightstick, the sound is of hard soled shoes, yet Sarah is barefoot.
When the Terminator grabs the guy in the yellow shirt, the guy says "ah ah get him off of me" but his mouth doesn't move.
When John calls his "foster mother" the T-1000 answers a Slimline phone, however, the Slimline phone has only one bell. The ring which was played when it was answered was that of a Western Electric 500 two bell phone. Also the sound of the ring itself doesn't come from the phone/ ring but old vinyl analogue source with a pitch fluctuations corresponding to uneven characteristics of this particular vinyl source and interval of pitch fluctuation per disc revolution.
When the T-1000 shoots his Beretta 92FS pistol in the hallway of the mall, the reports are muffled and distorted as if suppressed, yet the pistol has no silencer attached to its muzzle.
When Dyson and a security guard first open the vault containing the T-800 chip and arm, the guard says "3, 2, 1" but can be seen mouthing "1, 2, 3". Dyson later also counts "1, 2, 3" with John.
Camera lights reflected in glass in shot behind Dyson as Sarah Connor laser-scopes him.
At Cyberdyne, the Swat Team Leader says, "OK, drop him," and they start shooting. In the background, on the left-hand side of the screen, one crew member wearing a white T-Shirt walks into shot and exits left. (Widescreen DVD)
Camera is clearly visible in the elevator door when it closes as the trio escape the explosion at Cyberdyne.
When the T-1000 is about to kill the security guard in the mental institute a crewmember is reflected in of one of the vending machines.
Camera in protective box visible on the side of the truck.
When John is fleeing up the canal, he is obviously going "upstream". He takes a narrowing, converging fork and the canal gets smaller. When T-800 jumps the bike into the canal, he does it from a point that would be dividing the rushing water rather than converging it, hence, they are now inexplicably going "downstream". A flood control system NEVER diverges the water, it only collects it into bigger and bigger canals toward a common destination.
Shots of the canals and overpasses are out of sequence during the chase.
If the T-1000 can mimic any person or form it touches, there is no logical reason why it keeps reverting back into the form of Robert Patrick dressed as a cop once the Connors are aware of this guise. It could achieve its mission objective far easier if it used other forms to conceal its identity and then kill the Connors before they even realized.
POSSIBLE EXPLANATION: It is probable that the T-1000 knew that a uniformed police officer would be the form of human most likely to be let alone and permitted to go anywhere he pleased without being questioned or otherwise hindered, especially at security checkpoints like the prison's gate and front desk. And indeed, he is always just waved on through or buzzed in without question at these spots.
Near the end, the T-1000 tells Sarah to "call to John" to lure him out. The T-1000 had touched Sarah, and therefore could imitate her (we know this is possible because it had already done so for John's stepmom). Rather than try to get Sarah to call to John, the T-1000 simply could have done so itself and saved much time and effort in the process.
When they first steal the station wagon, Sarah tells the Terminator to drive the speed limit to avoid being pulled over. Later, at night, the Terminator is driving without headlights. Despite being able to 'see everything' due to his infrared vision, driving at night without headlights is a great way to attract the attention of police.
At several points in the film, Terminator makes it clear that killing based on the slightest human opposition or threat is natural to him and expected, being a Terminator, yet he does not kill the owner of the biker bar, who threateningly fires a weapon to warn him, once he acquires the weapon from him and is free to dispatch of him accordingly.
Terminator goes straight for, and easily finds, John in the back area of the mall, despite having no idea where he was in the entire massive, heavily-populated building.
John says, "Okay. Time out. Stop the bike." After that, he and the Terminator pull up into an alley and stop. After they stop, you can briefly see the reflection of the boom mic on the mudguard of the motorcycle's front wheel.
When Sarah is approaching Dr. Silberman after she breaks out of her cell, as the camera pans around the corner to show him, a boom is seen above the doorway to the cage area. (This depends on transfer, though, because of the adjustable framing; it's visible on the original DVD and Ultimate Edition DVD, but not on several widescreen laserdiscs. It may be visible in the 4:3 transfer, but that shot is cropped more than opened up and if it is visible it would be in the overscan area.)
In the mental hospital, after the Terminator takes out the orderlies trying to sedate Sarah, The T-1000 approaches with a loaded weapon and clear line of sight to John. Seeing as his only mission is to kill John, he could have easily shot at John who was occupied trying to calm Sarah from the other side of the bars. But instead he walks slowly up to the bars then passes through them before attacking giving them time to react and run away.
The security guard at the institution looks at his cup, which has 2 Jacks, 2 Aces and a Queen, and he shouts out "Hey, I got a full house." 2 pair is not a full house.
In the biker bar, the Terminator scans various people for body types and clothing matches. The body type descriptions do not always match the individuals he is scanning.
(at around 49 mins) Sarah tells Dr. Silberman that there are 215 bones in the human body. An adult has 206 bones, beginning with 270 bones at birth, a number of which fuse by adulthood, resulting in a final count of 206. If Sarah broke his forearm completely, this would mean breaking two bones - the radius and the ulna. In fact, she did not strike his arm but his wrist at the base of the thumb, which means she broke his hand, not his arm.
For a merciless killing machine on a mission, the t-1000 doesn't take his mission very seriously at times.
In the arcade, he is seen walking down the stairs instead of running to catch John, and there are several other scenes in which he can be seen menacing his victims rather than immediately dispatching them. (Walking through the bars, wagging his finger, etc)