Alternate versions

In the teaser trailer and the next 2 theatrical trailers some shots from deleted scenes are shown.

• Cliff Booth see Charles Manson walking away from Sharon Tate's house. Both exchange looks. Charlie initially greets Cliff, later Charlie grunts at him.
• Sharon Tate dancing in a black dress in a moving stage.
• Mr. Schwarz salutes the projectionist before entering the projection room.
• Sharon Tate swimming in her pool.

The version of the film that screened at The Cannes Film Festival was 159 minutes, two minutes shorter than the version released in theaters in the US. Tarantino reportedly added in more scenes of Sharon Tate, including extending the scene where she picks up a hitchhiker.

In October 2019, an extended cut of the film was released in selected theaters with an additional 10 minutes, made up of 4 new scenes which include an extended version of the opening scene, two fake commercials and a new after-credits scene.

In January 2020, Collider indicated with Quentin Tarantino that an extended version does exist and may be released "within a year".

"Once Upon a Time in Hollywood" is planned as a mini-series, similar to what was done with "The Hateful Eight," which was presented in four parts. According to Kyle Buchanan (The New York Times), Tarantino has promised some actors that he will include their deleted scenes back into the movie for the later version. One of these actors, Nicholas Hammond, confirmed this: via Playlist: "There is talk about there being a 4-hour Netflix version, as well, because there were a lot of scenes he shot that couldn't make it into the film because there just simply wasn't room [...] The promise is that like his other film, The Hateful Eight, they just done a 4-hour Netflix version. And I think they're talking about doing the same. There are some actors like Tim Roth, wonderful actors, who never even made it into the film. I mean, they're entire roles got cut...The Netflix version will be great too."

Tarantino on the two minutes added to the Cannes release: "Time-wise it amounts to two minutes. I was very happy with the Cannes cut. There is such a thing as taking yes for an answer. One of the things I wanted to do, though, was risk cutting the movie too tight for time. Everyone always goes to Cannes a little bit lumpy." In an interview with Deadline, the director has revealed what has changed since the Cannes premiere. There are two important additions. First, there is the scene from the Steve McQueen movie The Great Escape, in which it's not McQueen who has the leading role, but DiCaprio's character Rick Dalton. The scene required special effects that weren't ready for Cannes. Also extended was a scene with Margot Robbie as Sharon Tate as she's taking up a hitchhiker in Westwood. However, at the very end of the post-production Tarantino removed two short, unspecified scenes that were shown back in Cannes.