Oppenheimer stars Matt Damon and Cillian Murphy know the routine with director Christopher Nolan, having worked with him on previous movies: Nolan makes a call, they meet, the actor reads the script while Nolan waits nearby.

What Robert Downey Jr. didn't know is that those scripts are presented in a low-tech manner, which ended up being the Iron Man actor's one complaint about working with the filmmaker.

"I went over to his house. I read it," explains Downey in EW's Around the Table with Nolan and the cast. "I don't want to complain, but it's on red paper printed in black, which is kind of difficult at best."

"And a bit unnerving as well," interjects Emily Blunt, who plays Oppenheimer's wife Kitty in the film.

"I guess there's something about it that makes it that you forget it as soon as you read it," jokes Downey, who portrays Atomic Energy Commission chairman Lewis Strauss in Oppenheimer. "I don't know what those colors are. Anyway, it's a thing. You read the script, it's written in the first person, you're transported, and it's a journey to read it, and then at the end of that, the guy who wrote the script you just read is asking you if you want to do it. It's kind of like being hypnotized."

As it turns out, the red paper doesn't have any hypnotic powers at all — the color just makes it difficult to photocopy the pages.

Blunt, who is also a Nolan-movie first-timer, admits that she didn't realize she was actually being offered a role when she first met with the director.

"I went and met Chris in L.A., and I didn't know the process — I didn't know if you were meeting countless other people," she says. "So we talked for an hour or so, and then he's just very casual, and he goes, 'So it's the part of his wife and I'd love you to take a look at it.' And you're like, is this an offer? [Laughs] So I went into the living room and read the script and it was just so heart-racing. It was so awesome."

Blunt reveals that she called Murphy, who has appeared in a slew of Nolan-directed movies, to ask what she could expect from the experience of working with the filmmaker.

"I knew Cillian from A Quiet Place II, so, of course, I called him and I said, 'What's it like? Come on, tell me," recalls the actress. "And he just said, 'You're going to just love it. You're going to love it. It's so focused, there's no chaos, it's very giving, it's collaborative,' and [he said] how amazing he was with actors. I think that is the great beauty of Chris. There are directors who are led by the visuals, or there are directors who are pretty good with actors, but you never find where someone is as mirroredly brilliant at both. So I was excited about the focus of it, I was excited about the screws getting tightened on everybody, and what that atmosphere will feel like on a film set."

Oppenheimer drops in theaters July 21.

See Nolan and his cast reveal more about the making of Oppenheimer in the full Around the Table video below.

EW's Around the Table interview was conducted prior to the start of the SAG-AFTRA strike.

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