Plot hole: As the gun-toting Norseman approaches the buildings, Garry smashes the single-pane window with his handgun. It is inconceivable that the glazing in a structure near the South Pole would be single-pane glass, that would provide minimal insulation and which could be broken so easily.
Plot hole: It's never explicitly stated or shown that the Thing reproduces with each victim until the movie is nearly over (when Palmer infects Windows). Most viewers figure it out from the context, but it's unclear just when and how the characters themselves have come to this conclusion. This was an inadvertent result of an editing decision and a visual goof: there is a deleted scene in which Blair explains much more directly that the Thing multiplies according to how many victims it takes, and in its place in the final film is a scene containing a computer simulation that director John Carpenter acknowledges was a failed attempt at explaining the organism's life cycle.
Suggested correction: This isn't a plot hole. It's explained in the computer scene that the entire world population would be infected 27,000 hours from first contact. That only makes sense if the organism reproduces. Even without that explanation, there's no plot hole. The plot still works. The characters come to a conclusion. They might have worked it out, guessed, or simply be wrong. Just because that's what they believe it doesn't make them correct.
True, it has "the effect" of a plot hole more than it literally is one in itself, but it's the closest category for a pretty unique expository failure for a major studio film; one confirmed to have been a total goof in the production. All we have for most of the film is the implication of the word "infect" going up against VERY clear and misleading exposition of the Thing's nature. I'll consider changing the type to "Other," but I feel strongly it should be represented.
