Leonardo DiCaprio went to such great lengths as a method actor on “The Revenant” that he devoured a raw slab of bison’s liver. Although the props department had constructed a faux liver from jelly, DiCaprio worried that it didn’t look right. And so — after calls to his lawyer and agents cleared — producers were able to serve him the real thing. “The bad part is the membrane around it,” DiCaprio says. “It’s like a balloon. When you bite into it, it bursts in your mouth.”

Director Alejandro G. Inarritu says he was initially concerned that his leading man could get sick from eating a potentially disease-ridden organ. But, he now beams at what the real liver added to DiCaprio’s performance. “Without it, he may not have gotten to the truth,” Inarritu says.

Art Streiber for Variety

In preparing to portray Hugh Glass, a real-life 19th century explorer who survives a brutal bear mauling in order to avenge the death of his son, DiCaprio also had to learn how to shoot a musket, build a fire, speak two Native American languages (Pawnee and Arikara) and study with a doctor who specializes in ancient healing techniques. He calls it the hardest performance of his career.

“It was like the real wild, wild West in the sense that there were all these cultures merging together in this lawless land,” says the 41-year-old actor.

The same could be said for the grueling production of “The Revenant” which was plagued by severe weather, runaway costs, on-set quarrels, staff defections from the large crew, and other problems reminiscent of DiCaprio’s troubled shoot aboard 1997’s “Titanic.” The actors entered into a real-life frozen jungle during a seven-month shoot in Alberta, Canada, using natural light (shot by cinematographer Emmanuel “Chivo” Lubezki) and fending off frostbite in temperatures that plunged to 40 degrees below zero. If that wasn’t grueling enough, a lack of snow near the end of the shoot forced the production to shut down last spring, and add six days in July — mid-winter — in Argentina, which tacked millions to the already inflated budget, while Inarritu had to cobble together an edit without an ending.

“I just want to set the record straight,” DiCaprio says over several glasses of wine during a 75-minute interview at the Beverly Hills Four Seasons, with Inarritu by his side. “There’s been a lot said about the movie and the difficulties making it, and how meticulous Alejandro is with his vision. But to me, that’s the shit that should be praised. I don’t want to work with somebody who isn’t thinking of every possible aspect of what’s up on the screen. I think there’s a hunger for audiences to see something completely extreme and difficult.”

So hope the film’s backers, New Regency, Brett Ratner’s RatPac and Twentieth Century Fox. The team is banking on the $135 million epic tale — which debuts in limited release on Christmas Day and opens wide Jan. 8 — becoming a commercial success as well as a major awards contender that could land DiCaprio, a four-time Academy Awards-nominee, his first Oscar.

Hollywood has a tradition of movies that bring crews to their breaking point — one that harks back to films like David Lean’s “Lawrence of Arabia” and Stanley Kubrick’s “The Shining.” Sometimes the films that result are masterpieces; other times, studios are left with the next “Heaven’s Gate,” which ran United Artists into the ground. Today’s film business is dominated by blockbuster comic-book franchises like “The Avengers” and literary phenoms such as “The Hunger Games.” It can be punishing to big-budget period pieces that fail to attract wide audiences (think Ridley Scott’s “Exodus”). “The Revenant” is a big gamble.

Art Streiber for Variety

“It’s hard to say what will happen, and whether the brilliance of this film will be rewarded relative to its costs,” says Sean Penn, who worked with Inarritu on “21 Grams,” and calls “The Revenant” a masterpiece. “I’d like to think we’re a culture that values its art enough to recognize we need this.”

DiCaprio is known for turning even challenging material like “The Wolf of Wall Street” and “Django Unchained” into global hits. But even coming off last year’s win for “Birdman,” Inarritu, the auteur behind small dramas like “Amores Perros” and “Biutiful,” has yet to direct a picture with a worldwide box office take that exceeds the budget of “The Revenant.”

Hollywood will be watching this latest pairing closely to see if adult material can in fact thrive against the odds. In person, DiCaprio and Inarritu couldn’t be more different. The actor still projects a boyish charm, unlike the scraggly frontiersman he plays onscreen, and he’s reserved. Inarritu, on the other hand, is a nonstop chatterbox of one-liners. He refuses a shot of tequila offered by a publicist, claiming he’s still haunted by “the ghost of my hangover” from the night before. At one point, he says he wants to talk about the art, before joking he did “The Revenant” for the paycheck. “I need my fee,” he says. “Careful,” DiCaprio warns him. “When you say something in print, sarcasm doesn’t translate.”

Inarritu had an exacting vision for the way he wanted to execute the story, which either inspired his crew or drove them nuts, depending on whom you ask. He demanded the production film in chronological order (he believes his actors’ performances benefit from living with each scene as the audiences does), in the vast wilderness, using long takes reminiscent of “Birdman.” New Regency greenlit the project at $60 million (with a second budget estimate coming in at $95 million), and continued to write checks as owner-billionaire Arnon Milchan watched the dailies.

“There was no panic on any front,” says Brad Weston, president and CEO of New Regency. “We knew what we were doing.”

The most dazzling sequence in “The Revenant” is the much-hyped, terrifying bear attack, which leaves Glass on death’s door. Inarritu is reluctant to give away any behind-the-scenes secrets. “It was a very well-trained animal,” he says with a smirk. “Let people enjoy it.” The scene was shot over several days in November last year, in a torrential rainstorm, which created added hardships, given that the fight is choreographed in one take, with rigs of makeup blood exploding over DiCaprio’s face. Inarritu had studied bear attacks on YouTube, and the special effects team had created an elaborate dance with the help of harnesses, ropes and stunt men who tackled DiCaprio as stand-ins for the beast. The bear itself is CGI. “When CGI works, in my opinion, is when it’s done in the real world,” says Ratner, adding that a computer-generated DiCaprio would have looked like a cartoon.

But it wasn’t just the rain that slowed “The Revenant” down. On a movie set, says veteran producer Mary Parent, who joined the crew in December as an extra pair of hands, “Everyone hopes for the best and prepares for the worst. I think the reality quickly became that the worst was going to be unlike anything anyone had encountered in terms of weather. It became the main nemesis of the movie.”

SNOW JOKE: “I got the flu quite a few times,” DiCaprio says. Inarritu adds that in one scene, when the actor let out a stream of phlegm, someone at a screening asked him, “Was that (dubbed)?”

Courtesy of 20th Century Fox

The cast set up shop overnight in small villages, and would drive — for up to two hours each day — to the uncovered set. “It was bizarre, because we were making a big movie with a small camera team,” says Lubezki, who wore six layers of thermal clothes to keep warm. “We didn’t have normal gear. We didn’t have lights.”

The lack of a cellphone signal meant that crew members had to relay messages via snowmobiles. The first few months were plagued by nonstop storms and threats of frostbite. But despite the harsh weather, DiCaprio insists he was never injured. He did, however, get sick repeatedly. “I got the flu quite a few times,” he allows. In one scene, where the other men in his troop carry him up a hill on a stretcher, Glass lets out a guttural cough. That’s not, in fact, acting, but DiCaprio spewing out phlegm. Inarritu tells a story about how, after a recent SAG screening, an actor approached him to ask: “Was that ADR?” Inarritu laughs.

The director admits he was a stickler for details. When he discovered there were no ants on the snow-trodden grounds of Calgary, he had them imported from British Columbia for a scene where they crawl over DiCaprio. “We had to fly the ants in,” Inarritu says. “Two flights, because some of them died in the first flight. They were panicked by the altitude. They fly first-class!”

He nicknamed a member of the crew “the wax lady”; she was tasked with rubbing balls of wax on the character’s costumes to create a more worn-out look. He even made sure the character’s footwear looked authentic while keeping the actors from losing their toes from the cold. “We had to build special moccasins that had protection and warmth,” Inarritu says. Adds DiCaprio: “And a grip. To give us a little traction, so we weren’t like a bunch of happy gnomes, sliding all over the ice.”

For much of “The Revenant,” DiCaprio is immobile and silent. The transformation required a Herculean effort from the makeup team, which included Sian Grigg and Duncan Jarman, who used 47 different prosthetics to cover DiCaprio with bites and wounds on his body, torso and back. “We did the neck laceration,” says Grigg, who was pushed to dial up the blood. “Alejandro wanted us to go back and make it look more grotesque.” DiCaprio would sometimes rise at 3 a.m., to sit through four or five hours of makeup, as the crew anxiously prepared for the two hours of sunlight per day with enough light to film. Further, temperatures continued to dip in Canada that winter, forcing the crew to wrap a week early before Christmas break. “We were doing makeup in hats and scarves,” Grigg says. “It was so cold in our trailer, our makeup bag froze to the floor.”

Art Streiber for Variety

But in the spring, the cast found itself with a different problem. Warm winds had suddenly descended on the area, making the snow melt in piles, a reality that Lubezki’s lens couldn’t hide. “That’s what climate change is,” says DiCaprio, who is making a documentary on the subject. Throughout March, trucks would drive in snow, but by April — for the film’s big battle scene between DiCaprio’s Glass and his onscreen nemesis, John Fitzgerald (Tom Hardy)— it became much too hard to pretend. “There was no way to do it,” says producer Steve Golin. “We had to find another option.”

That meant scouting other locations, and settling on Argentina. Inarritu estimates that 70% of the film’s overbudget costs stemmed from changing the location of the shoot, and he compares making a movie to rock climbing. “Once you start to establish the language of the film, there’s no way back,” he says. “You either go up or you die.”

While the production was shut down, Hardy had to drop out of “Suicide Squad” due to scheduling. “Was I bummed? Of course I was,” Hardy says. “I hate f—king losing work. I kept bemoaning they were losing me significant money on a daily basis. Actually, it was good for my character.”

DiCaprio returned to Los Angeles, sporting Glass’ scraggly beard. He wasn’t able to shave it off until late July, when he could finally shoot the film’s flashback scenes. “I had that beard for a year and a half,” DiCaprio says. “It becomes like a spouse. You sleep with it. It was like shaving off dreads.” Inarritu recalls hearing about a tabloid report that suggested the beard that been infested with fleas. “They are now homeless,” Inarritu jokes. “They are in Santa Monica.”

But that wasn’t the most salacious rumor associated with “The Revenant.” Of course, the Drudge Report was widely mocked for linking to a false story recently that claimed DiCaprio is raped by a bear in the film. And then there was a blind tabloid item that suggested Hardy decked his director one day over an on-set disagreement, which the actor denies. “If you hit somebody, you’d know about it,” Hardy says. “That didn’t happen.”

“The Revenant” is a throwback to a different era, when studios routinely took gambles on original stories. Today’s movie business is basically fractured into two different kinds of pictures: the under $20 million acclaimed adult drama (such as “Brooklyn,” “Carol,” “Spotlight” and “Room”), a genre that’s quickly shrinking; and blockbuster sequels (only one of the 10 top-grossing films of the year so far, “Inside Out,” is based on a new story).

“The Revenant” is a box office litmus test for one of the few A-list actors who has never headlined a sequel. “To me, every movie I’ve done has been its own piece of individual art,” DiCaprio says. “You read a script — it’s got a beginning and an end. It’s hard to envision that being resurrected again.” But despite being one of the biggest movie stars, DiCaprio reveals he’s struggled to get financing for his projects since 2006’s “Blood Diamond,” which grossed $57 million domestically. “When I did ‘The Aviator,’ that was a $100 million epic about a guy — Howard Hughes from the 1930s — consumed by germs,” he says of the 2004 Martin Scorsese drama. “I don’t think two years later, I could have made that movie for another five years. There are ebbs and flows. Now with the onset of great television, the era of poetic epics is almost nonexistent on the big screen.”

Inarritu offers that all Hollywood executives are terrified of launching a big-budget film around characters who aren’t familiar. “If it’s not based on a brand or a book that’s sold millions, it’s scary as hell,” he says. But DiCaprio thinks the movie business will get its edge back. “It might actually get better,” he suggests. “When you don’t rely on studio systems, there are the subscriber-based networks like Netflix or Amazon.” He’s not sure if the typical model of windows — which keeps movies playing in theaters for 90 days — will continue to thrive. “Who knows what the hell the future of theatrical releases will be?” he says. “But right now, certainly a film like this is a rarity.”

And while “The Revenant” may have pushed DiCaprio to his limits in more ways than one, Inarritu teases it could also bring the star another first in his life. “We’re planning ‘The Revenant 2,’ ” he deadpans, as DiCaprio rolls his eyes. “It would be funny. Pre-production starts next week.”