Shooting the scenes where Gyllenhaal had to act opposite himself presented both mental and technical challenges for all involved. Cinematographer Nicolas Bolduc recalls; “When I read the script I remember thinking, how the hell are we going to do the duplicity scenes? How are these characters going to be in the same scene at the same time? How is that going to feel? When we talked about doing the duplicity, our main concern was making it feel real.”
The production brought in a special motion control system called the Mo-Sys, which can be programmed to repeat a precise camera movement more than once. This allows the team to shoot the same scene over and over in the exact same way, making it possible to do one take with Gyllenhaal as Adam, then reset and do the exact same movement with the actor’s other character, Anthony.
The biggest challenge with the duplicity scenes, however, was finding the best way for Gyllenhaal to interact with himself. For some scenes, an acting double was used to perform opposite Gyllenhaal. The double was then erased and replaced with the actor’s other character. In other scenes, Bolduc would stand in as Gyllenhaal’s other character. “Everything went really well with the use of the Mo-Sys but we realized that the most important part of Jake acting with himself was his eye line – he needed to appear as if he were looking right at the character opposite him,” recalls Bolduc. “I used a C-Stand with a tennis ball as Jake’s other character and would have to verify its position after watching the previous shot on the monitors. It’s an incredible process because it was fairly simple, but Jake really had to trust the process and I had to trust what he had done previously with the other character.”