Factual error: The film takes place around 1830, but you can see a character using a Colt Navy 1851, which was made 21 years later actually.
Visible crew/equipment: When the characters walk through the snowy woods, just before reaching the cave, Colhoun kicks a patch of snow that seems to fold in half, as though it is a towel or blanket.
Continuity mistake: When Guy Pierce is offered a nut by Jeffrey Jones, Jeffrey Jones picks up a book in order to smash the nuts. When the book is first seen, the spine of the book is in his right hand. After smashing the nuts, the spine is in his left hand. Then when he goes to replace the book on the shelf, the spine in now back in right hand.
Visible crew/equipment: In order to escape, the lonely Cap. Boyd is struggling to walk down the mountain at the upper right side of the screen, but there is a quite calm man standing at the bottom left corner at the same time, apparently watching the main actor's (or his stunt's) performance. To make it worse, then another member of the crew arrives and both seem to wear modern clothes. (00:52:20)Tsavos