Greta Gerwig Watches 'Barbie' Screenings for Audience Reaction

American actor and writer Greta Gerwig is revealing an unexpected detail about her critically acclaimed film, 'Barbie', reported People.

The 40-year-old filmmaker explained that she made the decision to do her own clandestine fieldwork during the movie's opening weekend in July by hiding in the theatre's back during showings to observe the audience's response first-hand.

"I went around to different theatres and sort of stood in the back, and would then also turn up the volume if I felt it wasn't playing at the perfect level," she recounted during a screen talk on Sunday at the BFI London Film Festival, according to The Hollywood Reporter.

She said at one of those sneaky screenings, she heard a woman cracking up over a particularly zingy one-liner about the Proust Barbie. "And I was like, 'That joke was for you!' " Gerwig told the festival audience.

According to People, Gerwig went on to share that the film was "the most joyful" experience she's ever had on a set. "So, I thought, if I can make a movie that is half as fun to watch as it was to make, I think maybe we've got a shot," she said.

Gerwig also said that she occasionally struggled with self-doubt with the writing and some of her artistic decisions, such as the adored "I'm Just Ken" dance scene, which depicts the numerous Kens fighting.

"That sequence, in particular, was just filled with choices that thrilled me and made me so happy, but then I'd be driving home at the end of the day and thinking, 'Oh no!' " she recalled.

Gerwig is focusing on brand-new artistic endeavours as she continues to enjoy Barbie's record-breaking success. She made light of the fact that she was presently working on anything new by withholding further information.

"I'm in the writing process," she said at the festival, adding that she is still grappling with self-doubt. "It's hard because I'm having recurring nightmares."

In July, Gerwig echoed that same sentiment when talking about another upcoming project that will see her directing two Narnia movies, based on acclaimed British author C.S. Lewis' classic The Chronicles of Narnia book series, reported People.

"I haven't even really started wrapping my arms around it. But I'm properly scared of it, which feels like a good place to start. I think when I'm scared, it's always a good sign," she said on the Inside Total Film podcast.

"Maybe when I stop being scared, it'll be like, 'Okay. Maybe I shouldn't do that one.' No, I'm terrified of it. It's extraordinary. And so we'll see," Gerwig continued.

"I hope to make all different kinds of movies in the course of the time I get to make movies, which -- it's a long time, but it's also limited," she added. "I want to do big things and small things and everywhere in between, and having another big canvas is exciting and also daunting."

Sometime in the future, Gerwig also hopes to dive into the Barbie universe again and bring fans even more movies. "There's a tone and a humor and a joy, and obviously the world is so beautiful," she told People in July, declaring, "I want to go back to Barbie Land."