Irwin, who played TARS — the AvaTARS, if you will — bantered well with the film’s cast, and brought a great deal of humanity to a robot that is essentially a stack of folding cubes. TARS has no physical human characteristics, resembling one of the less popular Rubik’s puzzles than a traditional humanoid android. In a 2014 interview with the Hollywood Reporter, Irwin revealed that Nolan kept him on set throughout the shooting of “Interstellar,” an unusual practice indeed. On a more traditional set, TARS’ dialogue would have been spoken off camera by a P.A. or assistant director, giving the on-camera actors something to respond to. Then, later, the voice actor would come in and dub their dialogue in a recording booth. For Irwin, he gave TARS’ performance live, and then dubbed over his own voice later. 

Irwin also had a scare when preparing for the role of TARS. Irwin would carry his script everywhere, reading it and memorizing his dialogue, trying to get the character right. This meant taking the script — a high-profile, top-secret script written by Nolan and his brother Jonathan — into public places. There was even a moment when a grocery store worker could very well have absconded with Irwin’s copy. Irwin said, “I set my script down once at Ralphs grocery store in L.A., and I walked away from it for maybe all of three minutes. I’ve never been so scared in my life.” Luckily, Irwin was able to run back and grab it before anyone else caught a glimpse.