Other mistake: When they raise the temperature of the room with the facehuggers in, once the room is at body temperature, they open the door onto the much colder corridor. This would have immediately dropped the temp in the facehuggers' room.
Other mistake: When Lydia tells the ghost Nadia that she's having a "really shitty day" with her back to the camera, you can see she's not really talking and is actually putting a pill in her mouth. The dialogue was just dubbed over it. It then cuts to a different angle and we see her repeat the exact same motion as she takes the pill a second time between cuts.
Other mistake: Irs stabbed Richard completely through his face and shot him in the torso. Although he fell in the lake, he is later shown on the shore and he is not bleeding. Head wounds normally bleed like crazy. Since he is wounded in two places, he should have drowned or bled out from swimming to shore. (01:19:51 - 01:25:08)
Other mistake: When Cecilia finds the newspaper clipping with her own story, the headline is about Cecilia Jones, but the article ends with "Our thoughts and prayers go out to the Adams family." She was the only one involved in the accident. (00:48:30)
Other mistake: The car door behind the woman before she gets killed was open, then closes in the next shot. (00:23:00 - 00:24:00)