Charlize Theron had eight personal trainers to help her master her intensely physical performance. She also trained with Keanu Reeves, who was preparing for John Wick: Chapter 2 (2017).
Before filming resumed, James McAvoy broke his hand on the set of Split (2016) and had to endure all his action scenes with his injured hand.
The key fight sequence that unfolds in a real Berlin building lasts for almost 10 minutes in what appears to be an unbroken take when, in fact, the sequence comprises almost 40 separate shots seamlessly stitched together. Though filmed chronologically from start to finish, nearly half the splices needed some degree of CGI assistance. Swish-pans provided the simplest solutions for smooth cuts and door frames provided vertical seams for smoothly bridging some segments.