Continuity mistake: When they are all outside and MacReady has separated the three most likely suspects and orders that they be tied down and tested, he comments at that time that they are to be hit by a storm in six hours. Cut to the scene where Mac is dictating into his recorder and he comments that the storm has been hitting them hard for 48 hours. However it is the same night and at best, maybe only an hour has passed.
Continuity mistake: When Mac is locked out of the complex by the rest of the team, who think he may be a 'Thing', Childs uses an axe to try and chop open one of the doors, leaving a HUGE hole in the middle of it. Later Childs returns to that same door and the hole is significantly smaller and at a completely different location on the door.
Continuity mistake: When the crew is outside and they're going to lock Blair in the tool shed, you can see someone nailing wood across the window on the front of the shed. The pieces of wood are horizontal. In the next shot (inside the shed), if you look at the window in the background, the strips of wood are vertical. When Mac goes back outside, the wood is horizontal again.
Continuity mistake: When the dog, aka the The Thing, is led into the dog pen for the first time we see the floor is covered in a thick layer of straw for the dogs to sleep on. This is seen every time except when Childs uses the flame thrower. We get a wide shot of the pen as it's lit up in flame and the floor is now completely bare of any straw. There are also none of the recently deceased dogs that were lining the floor, being converted into Things. (00:31:05)
Continuity mistake: Just a couple of minutes into the movie, Gary shoots dead the crazed Norwegian and the camera returns to MacReady. Now watch closely: When he gets up to help injured Bennings, he and his Jim Beam bottle are covered up to the hilt with loads of snow. But on the next shot, a split second later, his clothes are miraculously clean and the whiskey bottle as dry as you can possibly get it. (00:09:00)
Continuity mistake: When the stray dog is placed in the cage with the other dogs and starts to mutate into The Thing, one of the other dogs start biting a hole in the fence. We get a clear view of the hole in one close-up, and in the next shot as The Thing sprays liquid on the dog, and the hole in the fence is much bigger. (00:27:45)
Continuity mistake: When Doc is trying to revive Norris and his arms fall into Norris' chest, he is wearing long sleeves down to the wrist. In the closeup of Doc's arms being ripped off, the sleeves are pushed up to the elbows and the forearms are bare. (01:15:15)
Continuity mistake: When the thing is on the lab table, and the severed head starts walking away, Mack torches it with a flamethrower. At one angle, you can clearly see that fire is not coming out of the hose. It is just a fire going off in the doorway. (01:17:20)
Continuity mistake: When the remaining men find Macready holding a flare to a bundle of sticks of dynamite, the sticks go from being loosely and haphazardly bundled together to tightly tied together and then back again in a matter of seconds. (01:12:45)
Continuity mistake: After the Norwegians exit the helicopter, one of them goes to throw a grenade but accidentally lets go of it, and it explodes. In the shot where the man takes cover during the explosion, the fire clears out and there is soot around the helicopter on the snow, about six feet. A couple of shots later, as the Norwegian stands up, the amount of soot around on the snow has notably increased. (00:08:20)
Continuity mistake: MacReady and Doc return to the research station from the abandoned shack in the helicopter. The scene then cuts to the dog watching the two exit the helicopter in the window. In the shot where the helicopter is visible in the window, the dog is looking out of the window from the right hand side. In the next shot, it is suddenly looking out of the left hand side. This mistake has nothing to do with the angle of the camera. (00:22:35)
Continuity mistake: After MacReady and Doc have discovered the spacecraft, the scene cuts to a wide angle of them approaching one of the researchers looking into a dug up hole. Just as the wide shot ends, MacReady and Doc are standing right next to the man. The shot then cuts to a closer angle of the three and MacReady and Doc are now several feet away from him. (00:39:50)
Continuity mistake: After the scene where the Norwegian helicopter chasing the dog through the snow ends, the scene cuts to the research station. The first shot from the research station shows a sign: UNITED STATES NATIONAL SCIENCE INSTITUTE STATION 4. This close-up shows scratching and rotting all over. A few minutes later, as the helicopter arrives at the station, the scratching and rotting over the "4" is no longer there. (00:04:30 - 00:06:15)
Continuity mistake: When the Norwegian helicopter finds the dog running in the snow, the dog turns around to notice the helicopter, causing some of the snow around him to push upwards a few inches. The shot cuts to the helicopter, but when the shot cuts back, the snow is suddenly almost level with the rest. (00:03:35)
Continuity mistake: When MacReady says they are going to find out who's who, he tells Doc, Garry and Clark to move away from the others and one of them steps forward in MacReady's direction. MacReady then raises his flamethrower around the top half of his abdominal region. The shot then changes where the camera is in front of MacReady and the top half of his abdominal region is shown, but the flamethrower is nowhere in sight. The camera cuts to an angle behind MacReady and the flamethrower is back. (01:02:10)