Although the movie takes place around 1767, some of the soldiers use muskets fitted with percussion locks during the hunt. Such locks were patented in the first decade of 19th century and came into popular use after the Napoleonic Wars.
Mani would not have been called a "Mohawk", even by the Chevalier De Fronsac, as this tribe had not yet been granted this official unique name. In French, he would have been called an "Agnier", "Iroquois" or simply "Indian".
When Chatel is attacked by peasants in the beginning of the movie, he is struck to the right side of his forehead (it is clearly visible, as the wound bleeds profusely). Later in the movie, the bruise and stitches are on the left side.
The goof items below may give away important plot points.
The body of the young woman which is used as bait for the wolf is that of the shepherdess (the lady with the goat), who isn't killed until about an hour later in the movie. (The shepherdess scene was originally shot to take place much earlier in the film and when it was switched to later, they just hoped no one would notice the body was identical.)