Revealing mistake: In the shot where Benjamin is riding his horse to the top of the hill, the camera pans from left to right and in the distance is the British army. But if you look to the left the trees are way too huge (a bad scale). If Benjamin had ten militamen cut one down, it would have wiped out 1/4 of the British army shown.
Revealing mistake: When Benjamin and Harry are talking on the steps of the legislature of Charlestown after deciding to go on war with the British, you can see a man behind them with something in his ear, a hearing aid or earpiece. (00:16:30)
Revealing mistake: In the shot where General Cornwallis says, "Unless I'm dreaming..." The shot is through his telescope. Notice that he's on a tall hill but the shot is almost level to the ground and it's moving down.
Revealing mistake: When Tavington has sliced Benjamin across the back in the final battle, Benjamin falls to his knees and the bayonet on the end of the gun he's holding, which is supposed to be metal, jiggles like rubber when the gun hits the ground.
Revealing mistake: Gabriel is noticeably breathing when he is supposed to be dead.
Revealing mistake: During the battle at the end, while Martin and Tavington are fighting, you can tell the battle going on behind them is a blue screen because they are often moving slower than the battle and vice-versa.
Revealing mistake: The obviously painted backdrops of Charlestown showed that the scene was not shot in location.