The "wolves" in the film are a mixture of real wolves, wolf-dog hybrids (a breed of dog called a Czechoslovakian wolf-dog), and CGI.
The rudimentary dialogue spoken throughout the movie is a language invented for the movie.
The concept of alpha, beta, and other subordinate wolves was first used in 1947 in a study by Rudolf Schenkel of the University of Basel, and popularized by L. David Mech in a 1970 book titled The Wolf. Schenkel observed captured wolves to get his findings. However, he later disavowed his own terminology in 1999 after realizing he had been working with incomplete data. The popular view up until that point was that wolf packs were comprised of individual wolves with the alpha being the one who dominates the others through combat, as explained in the film. After studying wild wolves for thirteen years, he found no battles for dominance. What Schenkel came to realize was that packs were families, and that the alpha was a parent, with the others being their children.
Since blue eye-color had not developed in humans 20 000 years ago, the blue-eyed actors wore brown contact lenses for accuracy.
The film could not bear a "no animals were harmed in the making of this film" tag, as four bison were slaughtered for use on a skinning/hide-removal scene. The bison were dispatched humanely by staff from Longview Beef Jerky.