According to Liam Neeson's account, the temperatures were as low as -40 degrees Celsius (-40 degrees Fahrenheit) ??? in Smithers, British Columbia, where the film was shot. The snowstorms/scenes were real prevailing weather conditions, and not a cinematic illusion produced with CGI (interview: Episode #20.70 (2012)). The cast wore thermals under their costumes for additional protection.
Wolf attacks are extremely rare in North America. Only a mere handful have taken place, and mostly by animals infected by rabies. Joggers, hikers and people who have stumbled upon wolf cubs and dens are the primary victims of attacks. Wolves attacking a group of adults capable of defending themselves is unheard of, although wolves have killed thousands in Europe, Russia and Asia.
In his glowing review of this film, Roger Ebert stated that in his long career, this was the only time that he actually walked out of his next scheduled screening because it affected him so. "After The Grey (2011) was over, I watched the second film for thirty minutes and then got up and walked out of the theater. It was the first time I've ever walked out of a film because of the previous film. The way I was feeling in my gut, it just wouldn't have been fair to the next film."
The film was originally to take place in The Yukon Territory, Canada, but the producers insisted that it take place in Alaska as to be more relatable to American audiences. Joe Carnahan went back and forth to try to keep the film's plot in the Yukon, but eventually gave up.
Ottway mentions that the "Alpha male" challenges another wolf for dominance. The theory of the Alpha Male has been a proven myth, although still prevalent as being fact. Animal behaviourist, Schenkel studied two packs of wolves living in captivity and came up with the Alpha Male theory without studying wild wolves. His studies remained the primary resource on wolf behaviour for decades. More extensive studies have found that wolves live in families: two parents along with their younger cubs. Wolves do not have an innate sense of rank; they are not born leaders or born followers. No wolf has won a role as leader of the pack; instead, the parents assert dominance over the offspring by virtue of being the parents.