Continuity mistake: We see Sarah Jessica Parker well-dressed in red without a bra. When Bruce Willis remove her red robe, she's wearing a bra.
Continuity mistake: When Smith and Connor arrive at the Nakamoto tower and are exiting the elevator on the 46 th floor, you can see in several shots that Smith's suit is wet on the shoulders. However as he was going up the elevator the suit wasn't wet at all and even during the whole scene in the 46th floor, the suit changes from wet to dry as angles change.
Continuity mistake: When Mike Rogers's daughter is sleeping on his lap and his wife comes to ask him if he's coming to bed, in one shot the daughter is way up sleeping on his shoulder and in another, back down on his lap.
Continuity mistake: When Bessie is examining the cards she found under the desk, they constantly shift relative to each other between shots. (00:23:05)
Continuity mistake: In the hotel scene where Darby calls Gavin to give him the instructions to meet her the next day, he eats one of the chocolates on his pillow and throws it down. They show a close up of the chocolates. After Khamel murders Gavin, he walks to the bed, pulls the recording device and eats one of the chocolates. They are now in a different spot on the bed. (00:59:55 - 01:00:25)
Continuity mistake: When Jack shows Joseph the first hornworm the way he is holding the tobacco leaf changes when the camera goes from close-up to a wider shot. (00:51:25)
Continuity mistake: After Bruce proposes to Andrea and he drops her off at home, she is wearing the ring on her left hand when she is inside his car. But once she steps out of it, the ring completely disappears.
Continuity mistake: When Rita is being held by Barney in the cabin, she wipes the mud from her face with a white towel. In subsequent shots, her face goes from completely clean to streaked with smears of mud.
Continuity mistake: In the scene where Gard telepathically fights an alien, you see his nose bleeding. Then the alien explodes, and in the next shot of Gard's face, the blood under his nose has vanished, only to return in the next shot of his face.
Factual error: Andy is interrogated by the detective after the latest rape, as evidence in this one points to him. Problem is, the cop mentions that all the victims had visited Andy's office before their attacks. In real life, with information like that, he would have been a suspect and subject to questioning from the very first incident.
Visible crew/equipment: When Carol and Ted are waiting in the car, during the shot where it is raining, you can see the reflection of a crew member on the window. He tries to stay out of sight, but you can still see him moving.
Continuity mistake: Julia is apparently being helpful towards the stranger at the door. She is taking notes as he says his name and auto club card number. She is casting a visible shadow on the door, entirely gone in the close-up of the door itself. (00:08:15)
Plot hole: In the scene in the hotel, David sees the victim's head on the floor after the killer left. Later when David is in a hospital bed he is watching TV and the reporter claims that all the heads were in Judd's car. The killer would have had to have gone back into the hotel room to get the head of that victim after David saw it. She would have put it in her bag right away if she was saving them all. The bag was even left behind. (01:12:30 - 01:25:00)