Revealing mistake: In the scene where Carter drives madly down the road to get to Alex, and Billy is riding his bike along the street, just before Billy gets knocked off you can clearly see it is a stunt double.
Revealing mistake: You can see the plane intact even though it has exploded. It stays complete, there's just fire around it. (00:18:55)
Revealing mistake: When Alex is running through the woods and is sliding down the hill, just before he stops himself from being impaled by some branches, you can hear someway say "Look out." It can't be the agents following as they're too far away.