Cailee Spaeny wasn’t sure she’d end up fighting xenomorphs in Alien: Romulus, so she was pleasantly surprised to learn she’d secured the project on Instagram.

In an interview with Entertainment Weekly at EW’s Comic-Con 2024 video suite, the Civil War star recalled the moment she learned she got the part in the forthcoming sci-fi horror film. "I saw it online before anyone told me," Spaeny said. "[I said] ‘What? I got it?' I was on the set of Priscilla, and it was toward the last day, and I was just scrolling through Instagram like, 'What? Excuse me? That this happened is insane.'"

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Director Fede Álvarez, sitting alongside Spaeny for the interview, then chimed in to say that she shouldn’t have been too surprised. "I didn’t want anything in this movie to be impersonal or corporate," he said. "All of this cast, I wanted to tell them in person." After all, the material was meant for Spaeny from its original conception: "Maybe you didn’t pick up the part where I said, 'I wrote the movie for you!'"

Indeed, Álvarez previously told EW he crafted the project with Spaeny in mind. "I always knew it was going to be her. I almost wrote the movie for her," the filmmaker said in a recent interview with EW. "In a way, she's the audience. That's the big difference it makes when you bring in younger characters in their early 20s. It's not that the audience is that age necessarily, but we are as inexperienced as they are when it comes to dealing with the situation that they're in."

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Still, Spaeny joked that she feared she could have jeopardized her status in the movie with a faulty audition or meeting. "I’m really good at making things go wrong," she said at SDCC. "I could have ruined it in that meeting. Like, 'I wrote it for you!' And then I said something awkward and strange.'"

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Elsewhere in the interview, Álvarez revealed that he used well-timed sound effects to frighten the cast while filming. “We had a speaker that we were blasting all the time with all the sounds from the xenomorphs,” he said. “Every time I wanted to scare them without showing it, there was this big speaker that was just blasting horror sounds to freak them out.”

Costar Isabela Merced said that sound ended up becoming a crucial element of Romulus. "I do love how you incorporated it into the movie," she said. "When I walked out of the theater, I had to go through a parking garage after I watched it for the first time. And then I heard an alarm, like in the movie, because it was a parking garage, and I jumped because I was just fresh out of the movie. It’s effective. The sound design is incredible."

Watch EW's Comic-Con livestream above.