Garth Jennings was an impressionable 12-year-old when he first saw a pirated copy of First Blood, a film that, more than a quarter-century later, wound up becoming the inspiration for his own film, Son of Rambow.

“It was the first film I’d ever seen that wasn’t meant for my age group,” the British filmmaker said during a recent promotional stop in Dallas. “We didn’t understand the whole idea of Vietnam. What we saw was a man who was amazing at sewing up his own arm, having jumped off a cliff. There was a self-sufficient thing that blew our minds. I made my first home movie based on that character.”

Paramount Vantage

Will Poulter, left, stars as Olee Carter and Bill Milner is Will Proudfoot in 'Son of Rambow.'

It took much longer for Jennings and friend Nick Goldsmith to launch their feature film careers. But the duo, known by the nickname Hammer & Tongs for music-video work, always wanted to revisit their 1980s childhood and that strange moment of inspiration.

“It’s when we grew up,” said Jennings, who directed the film and developed the script with Goldsmith. “You write about your own experiences, and then you realize that you can’t transpose them to another time. It was a much more innocent time for us. We’d just discovered video and just inherited a video camera, and there were so many things about that era that were wrapped up in the story.”

The film follows a young boy (Bill Milner) who seeks to escape his strict religious upbringing. After viewing a pirated copy of First Blood, he forms a reluctant partnership with the school bully (Will Poulter) to remake the film using a camcorder and plenty of fake blood and weapons. But the production soon gets out of hand when word gets around school, then back home, turning the fun times into headaches.

While parts of the movie are autobiographical, Jennings said the characters are fictional amalgamations of real people.

Goldsmith, 36, and Jennings, 35, have directed an array of innovative music videos for R.E.M., Fatboy Slim and Super­grass. Their feature debut came in 2005 with an adaptation of The Hitchhiker’s Guide to the Galaxy.

Son of Rambow shows the same quirky tendencies, mixing live action with animation and incorporating an eclectic soundtrack. Gold­smith said that while nostalgia is important to their latest, more personal collaboration, it also speaks to more universal childhood themes.

“When we were writing the script, we wanted it to try and be timeless. You don’t have to know about the ’80s to enjoy the film,” Goldsmith said. “It’s about developing a friendship and not having any fear of the consequences. That’s what we were trying to capture, more than making a film about the ‘80s.”

The filmmakers were particularly excited when Sylvester Stal­lone, the creator of the Ram­bo character and star of First Blood, gave his endorsement.

“We were not just relieved. We were delighted,” Jennings said. “It’s a bizarre thing to say, but it was an affectionate homage to that movie. I didn’t want it to be a cheap joke at his expense. It’s so easy to do that. In a weird way, that movie inspired us.”

Son of Rambow uses a cast of inexperienced children — discovered following a five-month search — who weren’t even alive during the period when the film takes place.

But they still related to the mischief and playfulness of their characters, Jennings said.

“Getting child actors right is the hardest thing in the world. They had never acted before, so they were completely open to whatever we told them to do,” he said. “They just understood that these kids were doing something they wanted to do. They related to that.”