Sylvester Stallone, Bruce Willis and Arnold Schwarzenegger star in the film, which plays as a throwback to their 1980s heyday. The actors emerge unscathed from massive, bloody shootouts to crack wry one-liners, including some recycled from their own decades-old blockbusters.
The film was also distinctively old-school in its approach to action, using minimal computer effects in favor of stunt work and real explosions. Stuntman Kun Liu, 26, was killed during one such sequence while filming at a dam last year in Bulgaria.
Mixed martial arts fighter-turned-actor Randy Couture said the death during the second-unit shoot "changed the mood on the movie for a couple weeks, for sure."
Stallone, who also co-wrote the script, told reporters this week in London that there had been deaths during two of his previous films and "it's never easy."
Co-star Dolph Lundgren said in an interview that his stunt double was seriously hurt in the same explosion, which he called a "major accident."
"I could see like post-traumatic stress for a month after. Because he was very close to dying," Lundgren said of his double, who was hit in the eye by a piece of iron. "It made us all realize that yeah, it is a dangerous business. You have to watch your steps.
Couture and actor Terry Crews said there was no thought of closing down the film after the death.
"Stuntmen take these wonderful risks every day, like police officers, like firemen. It would be a shame to not finish," Crews said. "And we kind of galvanized around that. That was a big moment for all of us, where we were like, 'Let's go.'"
At the end of the credits, the film is dedicated to Kun Liu's memory.
But the stuntman's parents have sued Millennium Films and the movie's stunt coordinator, Chad Stahelski, claiming they were reckless in the preparations, training and execution of the stunt.
"That is a nice and thoughtful gesture to the decedent and his family, but certainly it does not absolve the responsible parties of his death," said Bill Karns, an attorney representing Zong Yu Liu and Yan Mei Bai.
Stahelski and Elizabeth Wolfe, a spokeswoman for Millennium Films, have declined comment on the case.