Factual error: Filbert is in the southwest corner of PA. It is very far out of the way of Harrisburg and completely off the route from Philadelphia to Harrisburg.
Deliberate mistake: When the red jeep is driven into the tree, two of the occupants are thrown through the windscreen with such force that they land about 15 feet away from the vehicle, one of whom was sitting in the back. But John, who was in the front passenger seat with no seat belt on stays put. Then calmly gets out seemingly uninjured? (00:32:30)
Continuity mistake: In the very first scene where Elliot comes home and finds Anna sitting on the couch we see that the handbag she has is black but a couple of minutes later it's changed to yellow.
Continuity mistake: When the woman shows the video at the Filbert restaurant of the man being mutilated by the lions, the position of her hand holding the iPod changes between the front and back shots. (00:24:25)
Other mistake: When the Jeep crashes and John gets out, he sits on the ground behind the vehicle and picks up a shard of glass that's supposed to be from the vehicle accident. Given that all the glass on the jeep shows to be intact, the glass couldn't have come from the Jeep as insinuated by the audio and placement of the shard.
Continuity mistake: After the private starts shooting and the group Mark Wahlberg is in breaks into smaller groups and starts running in the field ahead of the wind, his group consisted of himself, his wife, the little girl, Jess, and two women. One woman was heavyset wearing blue with dark hair. The other was thin with red hair. The next scene of them running ahead of the wind, their group now has two boys, one black, Jerry (I think), one white, Josh (I think), instead of the two women. (00:48:28)