Only one person quickly agreed to appear in Alex Gibney’s new Elon Musk documentary: Musk’s father, Errol Musk. “We also had Errol Musk in ‘Hello,’” Gibney says.

Ultimately, the director ended up speaking with dozens of Musk’s colleagues for the film. His first wife, Justine Musk, makes an appearance, as does his former girlfriend Ashley St. Clair. Journalist Kara Swisher, LinkedIn co-founder Reid Hoffman, Zoe Schiffer, and WIRED Global Editorial Director Katie Drummond also spoke with Gibney. Musk will be released in theaters nationwide on Friday. But the arrival of Errol Musk, who has a complicated relationship with the CEOs of Tesla and SpaceX, was a turning point.

“Everyone else was pretty persuasive,” Gibney says. “It was very difficult to get people to participate because the risk profile of being honest about Musk was high.”

Once Gibney had interviewed all of his subjects, he had enough material to create a nearly four-hour documentary, including a 10-minute intermission. The result is a damning portrait of a billionaire CEO, detailing how much of Musk’s genius is based on his own mythology and his formidable ability to promote the stock prices of his publicly traded companies.

Musk never agreed to an interview with Gibney. Instead, the director and his team researched Musk’s previous public comments and created a mock Elon Musk persona to appear throughout the film.

I spoke with Gibney earlier this month about his experience making the film, why he decided to make the simulated Elon so appealing, and the material he had to leave on the cutting-room floor.

This interview has been edited for length and clarity.

Alex Gibney on Creating a Mock Elon Musk

Zoe Schiffer: Alex Gibney, thank you very much for being here today.

Alex Gibney: Nice to meet you, Zoe.

Zoe Schiffer: This shouldn’t spoil anything, but the film was four years in the making. Elon Musk never agreed to an interview with you. Instead, your team looked back at the archives of everything he had said publicly and created a kind of mock interview that serves as a throughline throughout the film. Essentially, this plays into Musk’s idea that we are all actually living in a simulation. How did you decide on that approach?

Well, what were you going to do? He is the main character.

I actually thought that, since he was so outspoken about this simulation idea, we should lean into it cinematically. You should play in Elon’s sandbox and do mock interviews. I think that when we started developing the idea—using his actual words and actual audio recordings, but also putting them into a kind of avatar that we would design—we came up with all sorts of thematic reasons to do it.