Factual error: When the infected Palmer starts his transformation into the Thing, he has a series of fits and the creature 'falls', or leaps upward onto the ceiling. Watch closely...you can see a piece of paneling also 'fall' upward, when it should have fallen down. (01:23:20)
Factual error: In the kennel scene, MacReady fires at least 7 shots from a pump shotgun. That particular shotgun can only hold 5.
Factual error: At the beginning, MacReady dumps a tumbler of ice and scotch into his computer, which spews a shower of sparks as it shorts out. No electronic device, not even an old 1980s personal computer, sparks like that when shorted out. It simply goes dead.
Factual error: If you are at or near a pole, aka Antarctica, you either have 24-hour daylight, 24-hour night, or a kind of continual dusk-like condition. You don't have bright day and dark night at the same time.
Answer: Remember that he'd just spent the whole day investigating how something mysterious and horrible destroyed the Norwegian camp, so he's already in a spooked state of mind. Hearing the dogs screaming at night is already unusual on its own, and also reminds him how this whole episode all started with a crazed Norwegian trying to kill a dog. Deep down he knows whatever happened to the Norwegians is now starting at their own camp.
TonyPH
I 100% agree.