There’s a scene in Super 8 in which Joel Courtney flubs his lines in the amateur film-within-a-film that his character, Joe Lamb, is making with his school friends. It’s a grace note in a summer blockbuster already laced with more heart than usual amid its mayhem-filled tale of horrible, unearthly things escaping from spectacularly derailed trains in quiet Middle America.

It’s also to the credit of writer-director J. J. Abrams that he left it in there at all, since it turns out that Courtney was actually spluttering for real. “That was me,” the actor tells the Straight, in a call from Los Angeles. “That was a really hard scene. Those were new lines, and they were throwing me off, and I just, like, couldn’t get them right. All day. It was horrible.”

A filmmaker like Michael Bay would have made him do it until it was perfect. Bay probably wouldn’t have cast Courtney in the first place, since the 15-year-old Idaho native had precisely nothing on his film-acting résumé when Abrams and coproducer Steven Spielberg gave him the plum role in what’s touted to be one of the biggest movies of the year.

“Yeah, it’s still surreal,” Courtney admits. “It’s still really crazy, and I still haven’t wrapped my mind around it. People keep telling me it’s gonna be really big and it’s gonna change my life forever, but I don’t think I really understand how big it’s going to be.”

We’ll all know soon enough, though the cross-generational appeal of the film is a diabolically brilliant near-guarantee that it’ll rake in billions. After his rollicking 2009 Star Trek reboot, Abrams has essentially made his version of an early Spielberg movie, from its film-geek hook—a bunch of kids capture something on their Super 8 camera that the murderously no-nonsense military doesn’t want them to see—to its acutely rendered, late ’70s consumer-dream setting.

Courtney quite rightly reckons that Super 8 (which opens Friday, June 10, in Vancouver) is “so perfect” that it’s “like a two-hour flashback” for anyone in Abrams’s (or his parents’) age bracket. “Even Kyle said that,” he continues, referring to Kyle Chandler, who plays Courtney’s emotionally constipated dad. “Kyle was 14 in 1979, so it was spot on for him. He was like, ”˜This looks exactly like my room!’ ”

As for Courtney, he says he had no trouble grooving on a period that might as well have been ancient Rome for all the relevance it has in his young life. “It was really easy for me to get into the ’70s,” he says, “because if you looked one way, there’s all these cars from nowadays, and if you looked the other way, there’s all these ’70s cars, and there’s a hundred kids, extras, all in ’70s clothes and hair. It was insane to look at them, it was so crazy, and all the bikes were completely ’70s. It was so cool.”

For the record, the first-time movie star only had the one, aforementioned day of flop sweats and dialogue mishaps. Otherwise, he aced a role that required a quiet and soulful presence as much as it needed him to run around dodging both cold-blooded air force colonels and escaped entities from Area 51. When Lord Spielberg descended onto the set for a survey, Courtney reports, he didn’t need to offer any acting advice to the cast of teens. “He said that we were doing a really good job, shook our hands, and then he said not to get a big head, and not get too entitled,” Courtney says.

Pretty amazing, really, for a kid who visited his brother in L.A. with the half-serious notion that he might find some work. “I wanted to go down that summer and get a commercial and a hundred dollars,” he says. “And I got Super 8.” Probably more than a hundred dollars, too.

Watch the trailer for Super 8.