The Greatest Beer Run Ever star Zac Efron still can't believe film is based on a true story

In the just-released comedy-drama-war-movie The Greatest Beer Run Ever, Zac Efron plays John "Chickie" Donohue, a New York-dwelling merchant seaman who decides to deliver cans of beer to people he knows serving in the Vietnam War. Remarkably, the film is based on a true story, something which Efron was still having trouble wrapping his head around when he and director Peter Farrelly (Green Book) visited the PEOPLE/Entertainment Weekly studio at the recent Toronto Film Festival.

"It's one of those unbelievable, real-life scenarios that you just can't believe a guy got himself into," said the High School Musical and Neighbors star.

"The craziness of a person trying to bring beer to friends during the Vietnam War," said Farrelly, "and happening to land right before the Tet Offensive, which was the biggest battle of the war up to that point, and the turning point of the war, that's what blows my mind."

Efron also revealed that he had the opportunity to spend time with the real-life "Chickie," who related the story of his Vietnam adventure in his book The Greatest Beer Run Ever: A Memoir of Friendship, Loyalty, and War.

"Back in the day, he would have just been, I guess, insane," said Efron. "He's just one of those crazy guys that seems to land on his feet all the time. I think we've all had friends like that. In real-life, he just couldn't be more lovely and sweet and he enjoyed being a part of the filming process. He was there, he offered a lot of insights, and, so, yeah, I feel like I get a good vibe from hanging out with him. I think we did the story story justice and, once again, I just can't believe that this happened."

The cast of The Greatest Beer Run Ever also includes Russell Crowe, Bill Murray, Kyle Allen, Jake Picking, Will Ropp, Archie Renaux, and Ruby Ashbourne Serkis. The film is now available to watch in cinemas and on Apple TV+.

Watch that Toronto Film Festival interview with Farrelly, Efron, and other cast members above and see the trailer for The Greatest Beer Run Ever below.

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