The actor plays a Roman soldier in the movie and many of the scenes in Scotland took place in very cold conditions, and when boiling - instead of just warm - water was poured down the wetsuit Channing was scolded, but the filmmaker is glad it happened because it was when he wanted him to act his most angrily.
He said: "He was yelling and jumping into the cold water and we all thought he was joking.
"So I carried on my conversation for about two minutes before I realised it wasn't an act. That was just at the point where I was trying to make him feel at the end of his tether so it was advantageous in a way."
Kevin also admits part of the reason he used Channing in the film was because he wanted to turn him from a Hollywood star to a more "vulnerable" character.
He told The Guardian: "I wanted to break down this mighty, self-confident, all-American boy and make him vulnerable. "That was the Journey I wanted him to go on: to be taken to bits and put back together again."