According to Gina Carano, she was supposed to miss when she threw the vase at Michael Fassbender, but she had an adrenaline rush when they were shooting and smashed the vase against Fassbender's head. "Fassbender's crazy. He loves that shit," admits Carano. "He had no problem slamming me into anything. Actually, Steven Soderbergh told him once, 'We need to get this shot better when you slam her head into the wall.' And I was like, 'Damn, that thing's not soft!' Soderbergh is behind the camera and he's being really mischievous. He wants something bad to happen... Anyway, we were going for it and [Fassbender] slammed my head so hard into the wall I kind of lost it for a second. I kind of slammed a vase right into Fassbender's face, but he said he knew it was coming because he saw a flash in my eyes. And right after that happened I thought, 'I'm so fired. I'm going to lose this job,' because that was the first fight scene we did. But Fassbender, he loved training for the fight scenes."
Gina Carano underwent a six-week intensive tactical training course with Aaron Cohen, an ex-Israeli special ops fighter. She spent three hours a day in stunts and three hours a day with Cohen. During a particularly harrowing two-week period when Cohen was teaching Carano the art of surveillance and countersurveillance, he and his team tracked her via a GPS system installed in her car. He gave her a prop blue pistol to use as defense and intercepted her as she was coming out of a hair salon. "I just got extensions and was feeling so pretty and there he was," recalls Carano, laughing. "He taught me entry and exiting a building, clearing a room, he put a GPS on my car, he like, followed me around. He had me stalking people, he had people stalking me. They just put me with a soldier who had never done a film before either. We were just soldier and a fighter thrown together in these unique circumstances and got to know each other's backgrounds. I think that was the biggest part of my preparation."