Other mistake: The date on the tombstone above Annie says that Judith Myers was born November 10, 1947, and died October 31, 1963. That would make her 15 (not quite 16 yet) at the time of death, yet everyone says that she was 17 years old.
Other mistake: In every case, the pod needs hours to take over the human, but, in Elizabeth's case, she gets changed in less than 5 minutes. (01:24:00)
Other mistake: After David Warner kills a man with his long thin sword, he pulls the sword out and puts it back in its scabbard, but there's no blood on the sword or anywhere.
Other mistake: As the police lift the body of the 'dead' hotel clerk from behind the desk, you can see his eyes look around a bit.
Other mistake: During the denouement, there is a scene with the meeting between Simon and Jacqueline inside the doctor's cabin. Jackie opens the doctor's case where he keeps the surgical tools pulling it out from a drawer, and she does not place the box back in the drawer or closes it; we see the whole time she spends inside the cabin, so it'd be impossible for the doctor not to notice what happened. (02:08:25)
Other mistake: During her fight with ex-hubby Michael, Laura asks him in exasperation "will fifty dollars be enough?" then crosses to her purse and pulls out a hundred dollar bill.