Both Pitt and DiCaprio are being paid $10 million for the movie.
The movie's world premiere will be at the Cannes Film Festival in May.
The movie will compete for the festival's Palme d'Or, 25 years after Tarantino's "Pulp Fiction" took home the prize. The movie wasn't originally part of the competition line-up, as Tarantino was afraid the film wouldn't be ready.
The first trailer and poster arrived last month.
The first poster and trailer for the movie dropped last month. The trailer showcases the movie's 1969 setting, as Pitt and DiCaprio's characters look to make a comeback in Hollywood.
Watch the trailer here.
The film takes place in "Los Angeles in 1969, at the height of hippy Hollywood."
Tarantino described "Once Upon a Time in Hollywood" in a statement last year, calling it, "a story that takes place in Los Angeles in 1969, at the height of hippy Hollywood. The two lead characters are Rick Dalton (Leonardo DiCaprio), former star of a Western TV series, and his longtime stunt double Cliff Booth (Brad Pitt). Both are struggling to make it in a Hollywood they don't recognize anymore. But Rick has a very famous next-door neighbor ... Sharon Tate."
While Tarantino's February statement mentions Sharon Tate as a player in the movie, Tarantino previously said that the film would not center on Manson but on the year 1969. In fact, the trailer makes no overt mention of the Manson family.
It has been five years in the making.
Tarantino said last year that he had been working on the script for the film for half a decade.
"I've been working on this script for five years, as well as living in Los Angeles County most of my life, including in 1969, when I was 7 years old," he said. "I'm very excited to tell this story of an LA and a Hollywood that don't exist anymore. And I couldn't be happier about the dynamic teaming of DiCaprio and Pitt as Rick and Cliff."
It's a "'Pulp Fiction'-esque movie."
Deadline reported last year that DiCaprio would play an "aging actor" in a "'Pulp Fiction'-esque movie." "Pulp Fiction," Tarantino's 1994 classic, told a collection of interconnected stories.
At CinemaCon in April, Tarantino confirmed this sentiment by saying that "Once Upon a Time in Hollywood" is "probably the closest to 'Pulp Fiction' that I have done."
Margot Robbie is playing Sharon Tate.
"Tarantino is one of my bucket-list directors," Robbie told IndieWire in April. "As long as I can remember, I've been a huge Tarantino fan."
Robbie was on the initial shortlist of cast members Tarantino had reportedly approached for the film, including Pitt and DiCaprio, Samuel L. Jackson, Tom Cruise, and Jennifer Lawrence.
The rest of the supporting cast is stellar.
Damian Lewis, Dakota Fanning, Emile Hirsch, Kurt Russell, Timothy Olyphant, Scoot McNairy, Al Pacino, and longtime Tarantino collaborators Tim Roth and Michael Madsen are also supporting members of the cast.
Lewis will play the late Hollywood star Steve McQueen in the film, Fanning will star as Manson family member Lynette "Squeaky" Fromme, and Pacino is playing DiCaprio's character's agent.
Burt Reynolds was originally cast in a supporting role.
Burt Reynolds was originally cast in the movie, but the iconic actor died in September.
Following his death, Deadline reported that Bruce Dern would replace Reynolds in the movie.
Luke Perry is in the movie.
Luke Perry's final role will be in "Once Upon a Time in Hollywood." The actor died earlier this year after suffering a massive stroke, but completed filming on the movie before his death. He plays a character named Scott Lancer, which is also the name of the main character of the 1968 Western series, "Lancer," according to Entertainment Weekly.
It has "one of the most amazing screenplays," according to DiCaprio
Leonardo DiCaprio, who starred as a villainous slave owner in Tarantino's Oscar-winning film "Django Unchained," had high praise for Tarantino's latest script at CinemaCon in April.
"It's hard to speak about a film that we haven't done yet, but I'm incredibly excited ... to work with Brad Pitt, and I think he's going to transport us," DiCaprio said. "I'm a huge fan of 'Singin' in the Rain' — movies about Hollywood. As an LA native, having read the script, it's one of the most amazing screenplays. We are going to do our best job to make it fantastic."
Sony Pictures motion-picture group chairman Tom Rothman also said at the the event, "It's the best screenplay that I have had the privilege to read."
Sony will distribute it.
Tarantino chose Sony as the distributor for "Once Upon a Time in Hollywood."
Deadline reported that Sony beat out a list of competitors, including Fox, Universal, Warner Bros., Lionsgate, and Annapurna, and that Tarantino was impressed with Sony head Tom Rothman's film knowledge.
Tarantino's previous films were released by Miramax and later The Weinstein Co. Both were companies of the film mogul Harvey Weinstein, who resigned from The Weinstein Co. after bombshell reports accused him of sexual harassment and assault in 2017.
It was set to be released on the 50th anniversary of the Manson family murders, but Sony has moved it up by two weeks.
Despite Tarantino's insistence that the film would not center on Charles Manson, "Once Upon a Time in Hollywood" was initially set for release on August 9, 2019, the 50th anniversary of the Manson family murders.
The Hollywood Reporter reported that the film's release was set to coincide with the anniversary of the Manson family's killings of Sharon Tate and six other people.
However, Sony Pictures moved the release date for the film up by two weeks to July 26, 2019.