The film was shot entirely practically, meaning no soundstage, nor greenscreen, nor CGI. The actors and actresses were truly suspended over fifty feet in the air on the side of a real mountain in Utah.
To get the shots of the chairlift moving with the actors and actresses speaking on it, Writer and Director Adam Green and Director of Photography Will Barratt shot everything themselves, as the film's hired camera crew was too nervous to dangle at those heights.
At the Sundance Film Festival, Adam Green told a story about how the spot where they shot this movie was supposedly haunted by a suicide victim, who had killed himself in that very spot a year before. This was validated by an audience member during the Q&A at the Sundance Film Festival. She personally knew the victim. This info is also available as an easter egg on the DVD and Blu-ray releases. The person committed suicide on Chair 92 (which can be further identified with a hole in the seat) while the cast and crew used Chair 75 for the movie.
Emma Bell was the first person to audition for this movie. After sitting through weeks of other auditions, Adam Green hired her for the role, as she had set the bar too high for anyone else to compete.
Adam Green uses much of the same key crew positions in every project he does, and chooses his projects based on whether or not he can work with his friends. The man on the "Missing" poster in the lodge is Green's usual camera operator B.J. McDonnell who couldn't shoot this movie, because he had already booked work on Halloween II (2009). The poster is meant to be a shout-out, and a dig at B.J. for missing the shoot.
Filmed at Snowbasin Ski Resort in Ogden, Utah though the story takes place at a fictitious New England mountain called "Mount Holliston". Holliston is the town where Adam Green grew up. There are no ski mountains there.
The first night Dan, Joe, and Parker are on the lift, Joe starts a conversation about the worst way to die. Dan says to him, it would be being eaten alive by a shark, which leads to a discussion of Jaws (1975). One of the production companies for this movie is called "A Bigger Boat", a name taken from Chief Brody's line from Jaws (1975) ("You're gonna need a bigger boat").
When trying to find the right spot to shoot the movie, some of the crew were scouting the area from one of the chairlifts. One suggested a spot fifty feet above the ground and the chairlift, almost magically, just stopped. They knew right then and there that this was the right one.
Twisted Sister's Dee Snider is the voice from the top of the mountain who announces "Last chair is through." Dee's son Cody was the director's assistant on the picture, and cameos in the lodge wearing a Twisted Sister t-shirt.
The main characters are named after Adam Green's real life friends Joe Lynch, Dave Parker, and "Spooky" Dan Walker. Though the names were originally temporary names in the first draft of the script, everyone got used to them, and they stayed that way for the film. There is a moment when Lynch says to Dan, "That's kind of spooky, Dan" as a shout-out to "Spooky" Dan Walker.
This movie's UK Premiere was at FrightFest in Glasgow, Scotland, a festival, of which Adam Green is very fond, and attached, as he attends the London edition of FrightFest every summer, whether he is promoting a film or not.
Adam Green hit on the idea for the film just prior to going to Canada to start production on Grace (2009). As he was only a Producer, he could sit in a corner and work on the screenplay. He completed his first draft around about the time that filming wrapped.
Adam Green's old band "Haddonfield" performs on the soundtrack. After Parker (Emma Bell) strikes the deal with the lift operator, that is Green singing on the loudspeaker. The song is called "Among The Dogs".
There is a giant "Newbury Comics" billboard at the base of the mountain to help sell that the film takes place in New England. It is also a reference to Adam Green's first film Hatchet (2006) which featured the comic, DVD, and music store's "tooth face" logo on Ben's (Joel David Moore's) t-shirt.
The trivia items below may give away important plot points.
Kevin Zegers did the scene with the wolves starting to swarm around him (just before the actual attack) without a stunt double. When one of the wolves got too close for comfort, the trainers had to pull the wolves away, and filming had to stop. In the film, you can see a few frames of the black wolf walking right up into Kevin Zeger's face as Kevin tries to look away for help from the crew.
The script never revealed the exact way that Dan died, as the full horror of the situation was supposed to be reflected in the reactions of his two friends. Nevertheless, Kevin Zegers enacted a death scene, where he gets savaged by the wolves, on the off-chance it would be required for foreign sales.
The first time anyone ever saw this movie was at Ain't It Cool News' Buttnumbathon event in Austin, Texas, on December of 2009. It was a surprise screening, where this movie played alongside Shutter Island (2010), The Lovely Bones (2009), and Avatar (2009). One woman in the audience fainted, and was carried out after watching Kevin Zegers' character jump from the lift to the ice fifty feet below.