Stories started to swirl off the set of the film in the summer. Crew spoke of enduring a “living hell”, of being forced to work in -25C temperatures, of travelling for hours to remote locations in Canada and Argentina to film for a mere 90 minutes, the result of Iñárritu’s decision to shoot only in natural light.

“If we ended up [using] green screen with coffee and everybody having a good time,” the Birdman director told The Hollywood Reporter, “everybody will be happy, but most likely the film would be a piece of s---.”

Leonardo DiCaprio, who took the central role, had perhaps the most uncomfortable experience of all (discounting the extra who was dragged facedown and naked across an icy plain during a battle scene). DiCaprio’s sufferings in the name of art included spending the night sleeping in an animal carcass, plunging in and out of icy rivers and eating raw bison liver.