TonyPH

Plot hole: Dr. Tuskin warns that if Regan were to remember the events of her possession it could be so traumatic for her it could lead to suicide, even though Regan's therapy seems to be based almost entirely on what she can remember about the events of her possession.

TonyPH

Plot hole: The shuttle "won't take four" crew members. Considering it only has two cryotubes (and hypersleep appears to be necessary for any hope of survival), it doesn't seem to accommodate three people, either. (Admittedly I would still go for it, too, if I were up against a 7-foot-tall acid-blooded alien monster with two sets of jaws, but there doesn't seem to be much difference whether there's three or four people onboard).

TonyPH

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.

TonyPH