The well-known climber Ed Viesturs plays himself in the movie. He also worked as a trainer for the actors.
While the actual 28,000-foot K2 is in the Karakoram Range in Pakistan, Mt. Cook in New Zealand served as the backdrop for all scenes involving the famous peak.
Real-life high-altitude climber Ed Viesturs plays himself in this film. Four years earlier, he helped Beck Weathers descend Mt. Everest after Weathers was severely injured in the 1996 Mt. Everest disaster. Weathers survived a night in the open on the South Col, at 26,000 feet, and lost both his hands and was thus unable to grasp the fixed lines during the descent.
The toeless feet of character "Montgomery Wick" seen at the beginning of the film actually belong to mountaineer Mark Whetu, who lost his toes while spending a night outdoors above 28,000 feet during a 1994 attempt on Everest.
Montgomery Wick's name is an obvious reference to Thomas Montgomerie and Jim Wickwire. Montgomerie discovered K2, and Jim Wickwire was the first American to climb K2. Wickwire also lost several toes on the mountain, similar to the character Montgomery Wick.