Continuity mistake: Just after the doctor started the post mortem on that little girl, the front of his gown is covered with blood. Yet, a few seconds later, after the two other guys appear, his gown looks better, with less blood. And during the whole post mortem scene, the blood spot actually changes its size a few times. (00:17:55 - 00:19:55)
Factual error: The baby is expanded to approximately fifty times his height, width and girth but it's explicitly stated that he retains his orginal mass. This means he will have the same volume as one hundred and twenty five thousand babies of his original size, but will weigh the same as before he was enlarged! That child is going to weigh much less than the volume of air he displaces. He's going to float away.
Revealing mistake: Towards the end of the movie where Veronica Roberts hands are tied behind her back, she goes over to the mulching machine to cut the rope free. But as she hits the blades they bend and move like rubber.
Continuity mistake: During one scene, Mel Gibson is talking to the young boy through the treehouse door and holding the boy's jacket. The next scene, there is no jacket and then it magically reappears. (00:35:30)
Visible crew/equipment: When Ethan is going into the space ship, one of the critters pursues him. We then can see a man's shadow on the ground, most likely the cameraman's shadow. (01:04:15)
Visible crew/equipment: At the end when Dr. Angelo and Peter are escaping the blast, just after Angelo jumps down over the facility wall and calls for Peter to follow, for a second you can see someone holding the back of Peter's shirt to help him drop down, or it might be a rigging of some kind.
Continuity mistake: When Stone leaves the building he lives in, there is writing on the wall saying which way to go for each floor. When the killer enters the building, the wall is blank. (00:37:00 - 00:41:40)
Other mistake: When Tod is going outside to see a statue of himself, as he gets closer to the door he runs into it, but he actually jumps at the door.
Revealing mistake: When Nick returns to his apartment (after being made invisible) he immediately closes the curtains. Although he is invisible, we should see the curtains pulled closed at the point that he grabs them with his hands. Instead we see them close from the top, revealing they were closed either by a crewman or an automated process. Note: The curtains are NOT meant to be automatic in the film as we see and hear him physically close them.
Continuity mistake: Chapter 5 Abraham is shaving Director Po. It looks like he is just starting and Po is covered in shaving cream. They cut to Branick and when they go back to Director Po he has been completely shaved when it is clear Abraham has not done anything. (00:24:05)
Factual error: A digital billboard shows the date as "Thursday, November 23, 2009"; that date was a Monday.