By Sara Vilkomerson
Updated October 31, 2013 at 01:00 PM EDT
Unbroken 03
Credit: Vince Valitutti

Earlier this month Angelina Jolie began production on her second directorial feature, Unbroken, due in theaters Christmas 2014. The film is adapted from Laura Hillenbrand’s bestseller of the same name and tells the true and incredible story of Louis Zamperini, an Olympic runner who, while enlisted during World War II, survived a plane crash into the ocean. And that’s just the beginning of the trials Zamperini faced: he spent 47 days adrift on a raft in the Pacific only to then be imprisoned in a brutal Japanese POW camp for over two years.

“On set, we started to joke and say, ‘Tomorrow will be easier,’ knowing full well that on this challenging shoot, there are no easy days,” Jolie says via email. “Anytime it gets tough, we think of the real men who lived through this, and no one complains. In fact, we all just feel honored to be here.”

In the photo above, Jolie is on set in Australia’s Moreton Bay. For more exclusive photos, including one of Jack O’Connell as Zamperini and Finn Wittrock (with safety driver Carla Thexton), click through below:

Credit: Lewis Jacobs/NBC

Because production began with Zamperini (played by Jack O’Connell) and fellow airmen and raftmates Russell Allen Phillips and Francis McNamara (Domnhall Gleeson and Finn Wittrock) marooned at sea, the actors arrived on location in Moreton Bay starvation-skinny after an extreme diet protocol. “We’ve begun with the character’s lowest points, though, so I’m looking forward to when [Zamperini’s] in top form,” says O’Connell. “Perhaps the makeup will be less extensive so I might get a lie-in, compared to the current 3:30 a.m. calls.”

Kidding aside, the actor feels honored to be playing Zamperini, whom he’s met with twice. “Both times I came away feeling awe-struck,” he says. He has similar feelings for his director, whom he says he likes to think of as the World’s Best Boss. He’s not the only one impressed by Jolie. “She’s extremely bright and subtle-minded and absolutely devoted to getting it right,” says Hillenbrand, who speaks with Jolie regularly. “She wants every detail to be true. It’s easy to fudge things. It’s hard to be devoted to doing things right. She’s taking the hard path.”

As for Zamperini himself, now 96, Hillenbrand reports that he’s excited about the film — and its director: “He always says, ‘I volunteer to be in the movie as long as I can play Angelina’s boyfriend.”

Below: Jolie and first assistant director Joe Reidy (far left) watch over Domnhall Gleeson, who plays fellow survivor Russell Phillips.

Credit: Lewis Jacobs/NBC

For more on Unbroken, pick up the new issue of Entertainment Weekly, on stands Friday.