About 100 minutes into the film, the sound went out, drawing boos and jeers from the Paramount Theatre in Austin. The projectionist restarted the movie, which had been paused during a climatic scene, but the sound system failed again. After a third, successful attempt, the sold-out crowd burst into applause.
Afterward, Spielberg said "This is perhaps the greatest anxiety attack I've ever had."
The director, who received a standing ovation at the film's conclusion, asked the audience not to reveal any spoilers beforehand.
"This is not a film we made," Spielberg said. "This is, I promise you, a movie. A movie that's got to be seen on the big screen." He looked up. "And I'm wondering if this is a big enough screen.
"When I decide to make a movie, sitting in the audience with you, I direct in the seat right next to you. And your reaction is everything."
Also in attendance were cast members Tye Sheridan, Lena Waithe, Olivia Cooke and Ben Mendelsohn.
Before unveiling his new action opus, Spielberg made a confession.
"I'm a gamer," he said. "I've been a gamer ever since 1974, where I played the first Pong game on Martha's Vineyard while filming 'Jaws.'"
"But I really wanted to make this film with [novelist] Ernest Cline and my great screenwriter Zak Penn for people who don't play video games. This is not just a movie for gamers."
Every human being on Earth is in the target demographic for "Ready Player One," a sci-fi adventure set in 2045, where players compete through a virtual reality system named OASIS. The stakes are high, because the movie has an estimated budget of $200 million.
Spielberg made the trip to Austin to help boost its profile with SXSW's track record for helping launch studio movies into the box-office stratosphere. In 2015, the festival hosted a secret showing of Furious 7, which went on to gross $1.5 billion worldwide. Last year, it debuted Baby Driver, the sleeper hit of the summer of 2018.
In the Q & A session following the film, Spielberg said he read the script before he was familiar with the 2011 science-fiction novel on which the story is based. The project had an unexpected backer. "My wife, every day, she listened to the book on tape," Spielberg said. "This is not her kind of story. She never played a video game in her life. She came back to me after three days and said, 'Oh, you're making this movie.'"
The movie is packed with classic film and video game references, from "The Shining" to "Mario Kart." "Just remember one thing," Spielberg said. "The side windows are for cultural references. The windshield is for the story." But even he didn't catch all the allusions. "We made seven passes on one shot," Spielberg said. "And with the last pass, I said, 'S--! Is that a Gremlin?' ILN [Industrial Light & Magic] had snuck it in, thinking I wouldn't notice."
The special effects for Ready Player One took two years. During a lull period, Spielberg went out and shot The Post, the Oscar-nominated drama about Katharine Graham and the Pentagon Papers. "I've found when I have multiple projects, and I got lost in one of them, I'd come back to the other one with complete clarity," Spielberg said. "My objectivity is the thing that I fear the most about losing. I get too inside the story. I can't see it from the audience's point of view anymore. By doing several things at the same time, I guess I have a renewal of objectivity."
There was one notable exception to this rule: the time he made Schindler's List and Jurassic Park in the same year. "That was a horrible experience," he said. "I didn't want to be approving dinosaur shots when I was in Poland, doing the story of the Holocaust."
Ready Player One is out in cinemas in Australia 29 March.