Character mistake: When they're reviving Lindsey, Bud screams "fight" and slaps her. watch as she closes her eyes on the second slap while she is supposed to be dead.
Character mistake: When the T-1000 comes from the checkerboard floor and turns into the security guard at the mental hospital, the guard has just gotten a cup of coffee. On the side of the cup he has Jack, Jack, Ace, Ace. He looks at the bottom and says he's got a full house, but the card value on bottom of cup is Queen, which leaves him with only two pair.
Character mistake: When Guile promises to rescue the hostages while on camera with Bison, he makes it a point to mention Charlie by name to reassure him that he wasn't forgotten. Anyone in charge of a major hostage recovery operation would avoid naming a specific hostage unknown to the enemy due to the special focus that the enemy may put on that hostage for further abuse. This was promptly proven when Bison specifically chose Charlie to transform into a beast due to Guile identifying him as a personal friend.
Character mistake: While he is describing his origin, Dr. Manhattan mentions a circulatory system appearing at a military base. However, what is actually shown is a nervous system, as it depicts a brain and spinal cord.
Character mistake: When Lt Gannon is in the dogfight with the Russian jets, he announces that he is deploying "chafe and flares." The term is spelled and pronounced "chaff", and any pilot would know that.
Character mistake: Nick states that Wall Street was originally a wall (correct) built to defend against the British (incorrect). The original wall was a wooden palisade built in the 16th Century to defend the Dutch colonists against invading natives and to prevent livestock from wandering uptown.
Character mistake: There is a misspelling on the cover of the issue of Forbes magazine shown in the presentation about Stark's life. It reads "Tony Stark takes reigns at 21". The correct spelling of the word is "reins". Stark may "reign" at Stark Industries but he would take over the "reins" of the company.
Character mistake: When Carolyn first addresses Imam, she quite obviously pronounces his name "ell-mom," as though the capital I in his title were a lower-case L. It should be pronounced "ee-mam". We distinctly hear Ali call out his name in this fashion after the ship crash lands on the planet.
Character mistake: When Claire and Lowery look at the gyrosphere in red on the control panel, written above the gyrostation is "Return Request Disbhatched." Dispatched is misspelled. (00:55:20)
Character mistake: In the scene when Dave is checking out the failed transmitter at the radio station, Dave says "the bad news is your return loss - way too high". This is a mistake, as the movie makers got confused between the terms "return loss" and "insertion loss". Dave should have correctly said either "your return loss - way too low" or "your insertion loss - way too high".
Character mistake: Throughout most of the movie, many of the characters are seen wearing dark, heavy clothes such as long pants, sweatshirts, etc. Wearing warm clothing puts them at a greater risk of suffering heat stroke and dying more quickly, than if they wore light-colored, cooler materials.
Character mistake: An unloaded automatic pistol is much lighter and balanced differently than a loaded one. When McClane hands "Bill Clay" (Gruber) the empty pistol, a terrorist of Gruber's credentials should pick up on the odd balance (I notice that difference, and I very rarely even pick up a gun).
Suggested correction: This presumes that a person can notice the difference between a fully-loaded pistol versus a pistol that is empty, which makes sense. However, it would be much more difficult for a person to tell that a gun is completely empty versus one that only has one or two bullets loaded. Since Gruber has no way of knowing his ruse didn't work, he doesn't believe McClane would have given him a completely empty gun. He obviously believes there is at the very least one bullet in the gun. He's not planning on getting into a shootout with McClane, he is just planning to threaten him and he certainly doesn't need a fully loaded gun to do that.
Suggested correction: It's easy to tell the different between the weight of a loaded vs. unloaded pistol, but given Hans had never held the pistol before, he had no way to compare the weight. Unless he regularly handled that particular model of pistol (unlikely, given his pistol is a completely different make and model) he would have no point of reference.
Character mistake: The information on Walter's "patient information sheet" lists his address as 5962 Delco St but numerous shots indicate his house number is 238. (01:03:25)
Character mistake: After the first attempt by the kidnappers to get the ransom money, they tell the FBI to bring the money behind the Foo Chow restaurant. Clive gives Carter and Lee the exact same destination. Why in the world would kidnappers give the FBI a drop-off location exactly where they are based?
Character mistake: Thor calls Nidavellir "Nivadellir" the first two times he mentions it.
Character mistake: Close to the end, Madison is looking over the H.A.L.O. list on her laptop. When Dylan's profile pops up, her last name, Saunders, is misspelled as Sanders.
Character mistake: While posing as Steve's driver, Sameer refers to him as a colonel. He is actually wearing captain's epaulettes.
Character mistake: Near the end of the movie, John's wife calls one of his colleagues and says, "Jad, it's Laura, John needs a favour." Her character's name is Lara. (02:08:30)
Character mistake: After the Congressman is killed, the killer dumps pills on the floor of the car. Then the car is then rolled into the river. At about 15:07 the news reporter mentions that the Congressman's heart pills were found in his lap. This would be impossible because the pills and bottle would float and the pills would dissolve in the water. (00:03:45 - 00:15:05)
Character mistake: Once Santino and Ares find John again in the hall of mirrors, John is fighting two of the grunt men that came in with Ares and kills them. Both of which had light assault rifles and weapons on them. John and Ares proceed to empty their pistols out at each other before she runs off with Santino. John then throws his empty pistol away and gets up to pursue his target unarmed and while limping. It is unreasonable to think that someone with his skill and training and experience would not take two seconds to reach down and pick up one of the guns dropped by the two men he just killed before chasing after his target, especially given the highly trained body guard with him accompanying his target. As well as probable encounters with more grunts. To add to this, he was seen doing just this moments before when he had limited ammo and each time he'd down a few enemies he would pick up one of their guns and continue. (01:41:30)