"I had not listened to much Taylor Swift before the show," the actress—who plays Shayla on the hit Prime Video series—exclusively told E! News' Daily Pop on August 11. "When I got the show and I was reading the scripts—there's a lot of Taylor Swift in there—I became a big Swiftie. I'm in my Taylor Swift era now."
In addition to featuring several of the Grammy winner's songs, the series also debuted Swift's re-recorded version of "This Love." And according to Mills, the cast had no idea until the show's trailer dropped—and Swift shared it on social media.
"Normally, we get the trailers ahead of time, and we'll know when they're posting," the 20-year-old shared. "We didn't know anything. And then, I remember Lola [Tung] texted me. She was like, 'Taylor Swift just posted on Instagram.' I was like, 'What? Taylor Swift posted our show?'"
But Swift's involvement with the series wasn't the only exciting thing for Mills, as The Summer I Turned Pretty marks her acting debut. "It's been absolutely crazy," she told Daily Pop. "I feel like we were such a family on set, even the cast and the crew. It just felt like a little project you're doing with your best friends, and then it's like, 'Oh, the world's watching it. People are seeing me.'"
And like any family, they pulled off their fair share of pranks on set. "The thing is, once you get a prank pulled on you, you get to join it when they do other people," Mills explained, noting that co-stars Christopher Briney, David Iacono and Sean Kaufman were often behind the practical jokes.
"There was one they loved doing," she continued. "Chris had a speaker, and he would throw it into people's trailers, blast random songs—and then hold the door closed to your trailer. So, you're trying to figure out, music's blasting, you're like, 'Where is this coming from? How do I turn it off?' That was the signature."
With filming for the show's second season currently underway, Mills weighed in on the question that has divided fans all summer long: is she Team Conrad (Briney) or Team Jeremiah (Gavin Casalegno)? Turns out, it's neither.
"I will say this 'til the day I die, I am Team Cam (Iacono)," she revealed. "He treated her right. All this brothers and drama—and he was so good to her. He's a good boy."
Check out the full interview above.
The Summer I Turned Pretty is streaming now on Prime Video.