Pifias

At the point of the dinner scene, you can see both the doctor and Ginger not actually eating anything (the doctor eats air and Ginger waves her spoon around a bit for some reason), then somehow Ginger ends up with a rather large chunk of meat on her spoon that wasn't even on her plate.

When a werewolf is in the act of breaking through the door of Ginger and Brigitte's room, it is killed by the hunter's arrow through the head. The arrow is clearly shown entering the werewolf's forehead from in front. And then the camera pans up to show the hunter standing behind the werewolf, on the other side of the door, so that the arrow can only have entered the back of the head.

Later on when the fort's soldiers drag this werewolf's corpse out, this same arrow is now shown exiting from under the werewolf's lower jaw.

When the werewolf breaks into the fort, Brigitte's knife alternates between pointing upwards and downwards at least three times.

During the first leech scene (when they test if Brigitte is a werewolf or not) Brigitte's sock changes color from white to olive and then back to white again.

The movie states it takes place in 1815. All of the rifles/muskets used in the movie are percussion locks, not flintlocks. The percussion cap was invented in the early 1820's. Percussion style rifles did not start becoming prevalent until the 1840's. In fact many of the "Northwest trading companies" produced flintlock trade guns well into the late 1880's.

The film is set in the 19th century. The first interior shot of the main house of the fort shows a wax cylinder music box. There are six songs on cylinders, the first of which is the song "Sweethearts of Sigma Chi", a song not written until 1911.

Retrospective plot hole in the first movie created by this one:

This film establishes that the werewolf-disease is cured if the werewolf that caused it dies. In the first movie, the werewolf that attacked and infected Ginger is ran over by Sam's van less than five minutes after the attack. So, according to the logic of GS3, Ginger's transformation in the original shouldn't have even happened at all.

It's stated that the curse can be lifted only if the werewolf that bit the victim is killed by the victim's own hand. If the werewolf is killed by someone/something other than the victim, they lose their chance to break the curse.