A couple of somewhat surprising people had a significant hand in editing Joker, which picked up 11 Oscar nominations earlier this week including Best Film Editing for Jeff Groth. The film hailed from an original idea by Todd Phillips, who co-wrote and directed the movie, and he worked closely with star Joaquin Phoenix to develop this gritty, character-driven take on the titular DC Comics villain in a way that felt unique and impactful.

All films go through some sort of evolution in the editing room, and decision-making is crucial to a film’s success or failure at this time. In the case of Joker, Phoenix’s dynamic performance offered up a number of different options from scene to scene, but the film also plays with ambiguity and point of view in ways that make the piecing together of the narrative all the more important.

I recently got the chance to speak with Groth about his Oscar-nominated work on the film during a phone interview, and when I asked about feedback from “friends and family screenings”—during which cuts of the movie are shown to a handful of friends and family for notes—Groth says they didn’t really go through that process on Joker. Instead, the film was screened more personally for friends and filmmakers one or two at a time, including producer Bradley Cooper:

“We kept this one pretty close to us. We screened it more personally for people and filmmakers. Bradley Cooper definitely came in a couple of times. He was a producer on the movie, but he definitely watched the movie many times and sat with us. We could call him if we got stuck with something and be like, ‘Hey, can you come over and take a look at things?’”

Cooper obviously is a tremendous filmmaker in his own right, as evidenced by 2018’s magnificent A Star Is Born, and indeed he produced Joker through his shared production company with Phillips. Groth praised Cooper’s knack for picking up on small details:

“He doesn’t miss a thing (laughs). He would watch stuff and he would pick out even some of the smallest things and what are some of the things that he can be picked out for us to address. He was definitely a huge help. I think he got a lot more experience in editing than most people would realize.”

But Groth and Phillips had another significant collaborator in the editing bay: Joaquin Phoenix himself. It’s not entirely out of the ordinary for an actor to be involved in the editing process, but it’s not common practice either. For Joker, Phoenix had a key role in advising Groth scene-to-scene:

“I think probably he was in the edit room more that any other actor that I’ve worked with… What was interesting to have him come in is that he would always be looking to get the feeling from what was on screen to mimic the feeling that he had on the day [he shot it]. It was a really interesting perspective to have in the room. Of course, you’re putting together what you’re putting together, but then to have somebody saying like, ‘I lived that moment and here’s what I’m feeling.’ It’s another interesting perspective, so kudos to Todd for having him come in.”

Look for my full interview with Groth on Collider soon.