Plot hole: If Bradley Cooper was able to "quintuple" his money every day in the market as he claims to have done, he would have been able to earn the $100k he borrowed from a loan shark within a few days, starting from $800. Alternatively, he is shown in one scene winning a pot in poker where he could presumably also make a large amount of "seed" money from gambling. There was no need to borrow such a small sum of money from a loan shark, making the entire sub-plot unnecessary.
Plot hole: Through this film (and its predecessor) it is established that the creature imitates its victims perfectly, having all of their knowledge and memory. At the end, when the female lead tells the male lead she knew he was human because of his earring, he reaches for the wrong ear, confirming he is The Thing. Even if The Thing couldn't reproduce the earring, it would have known which ear it was supposed to be in.
Suggested correction: It is also established in this film that the creature cannot perfectly imitate inorganic materials; the tooth fillings, metal plate, etc. Kate knows that Carter is The Thing and asks him a trick question about his earring to confirm it. The fact that The Thing reaches for the wrong ear means that it didn't know where the earring really was because it cannot perfectly imitate inorganic materials. There is no mistake here.
The mistake has nothing to do with The Thing not being able to imitate inorganic material. The mistake is The Thing has all the memories and thus should know which ear was pierced based on these memories.
This goes with my theory that he was actually human because he didn't try to assimilate her when they we're alone and far away from people, and he didn't change when he was threatened and accused which was backed by (potentially false if the theory is correct) evidence which would make it defend itself.
You're obviously wrong here. The Thing imitates the human perfectly including the memory and I'm pretty sure that if you only have one ear pierced you'd know which one is it, therefore the imitation would know.
Plot hole: In the hospital scene at the end, why does Hicks run in and push Gale out of the way? She had no way of knowing someone was holding a gun on her and was about to be shot, as far as Hicks knew Gale was just standing there talking to someone. (01:40:00)
Plot hole: At the end of this movie, (1988) Kristi and Katie's mother died. In the first Paranormal Activity (2006), when the psychic is visiting he says it feeds off negative energy, and Micha says "I guess we can't have your mother over anymore."
Plot hole: After January Jones has just told Liam Neeson she doesn't recognise him. Neeson is trying to persuade Herr Strauss and two cops that he really is Dr Martin Harris of Langmore University, and suggests they look for a photo of him online. However, the cop using the computer says that it could take him ages to find a photo of Dr Martin Harris, as "there are more than 40 000 in the USA." This is very true, but as Neeson has already told him not only his name but also his place of work (Langmore university) in reality the cop would have found the photo far more quickly.
Suggested correction: The average cop wouldn't be that quick to realise that he could filter the results. Instead of being a plot hole, this is simply a very human initial response to an initial search result.
Plot hole: The very last scene shows Mary building a wall, apparently in her belfry. But there should still be the original wall that Rose built, with the hole in it that Mary smashed in. By killing Rose / having killed Rose, she prevents further harm, but all effects that took place before that (also the building of the wall), should stay (like her scars). It is very unlikely Mary broke down the whole wall just to add another body. (01:28:25)
Suggested correction: The main character says he did quintuple his money four days in a row, not that he could continue to do so. "Presumably" he could do anything, like robbing a bank. Gambling is not a secure source of income, even with knowledge of the odds and every tell, he could also lose a lot of money.