History Trivia / OnceUponATimeInHollywood

* [[Main/{{Corpsing}} Corpsing]]: During the scene where Sadie (Mikey Madison) derides Katie about “not knowing every facist on TV in the 50’s!”, you can see Creator/MayaHawke visibly trying not to laugh.

* ProductionPosse: As usual, Tarantino brought some veterans of his filmography in -- Creator/BradPitt from ''Film/InglouriousBasterds'', Creator/LeonardoDiCaprio from ''Film/DjangoUnchained'', Creator/BruceDern from ''Django Unchained'' and ''Film/TheHatefulEight'', Creator/KurtRussell from ''Film/DeathProof'' and ''The Hateful 8'', Zoe Bell from ''Death Proof'' and ''Django Unchained'', and Creator/MichaelMadsen from ''Reservoir Dogs'', ''Kill Bill'' and ''The Hateful 8''. He also gave a small role to Maya Hawke, daughter of posse member Uma Thurman. Two posse members, Tim Roth and James Remar, had their scenes cut but still show up in the credits. Tarantino goes as far as lampshading this in the credits, grouping most of his regulars under the heading "The Gang".

* ThrowItIn: A flashback shows Rick Dalton training to use a flamethrower, and recoiling from the heat it generates. This was Creator/LeonardoDiCaprio's genuine reaction to the flamethrower. Creator/QuentinTarantino thought it was funny, and left it in the movie.

* WagTheDirector: The original script had Cliff outright winning against Bruce Lee with a cheap shot, but Brad Pitt himself objected to it, knowing full well how bad it could look even with Cliff being an UnreliableNarrator.

** Creator/TomCruise was considered to star as Cliff Booth but had to back out due to scheduling conflicts with ''Top Gun: Maverick''.

** Rick Dalton's freakout in his trailer was unscripted. The whole tirade was improvised by DiCaprio.

* [[Main/{{Corpsing}} Corpsing]]: During the scene where Sadie (Mikey Madison) derides Katie about “not knowing every racist on TV in the 50’s!”, you can see Creator/MayaHawke visibly trying not to laugh.

* ActorInspiredElement: Creator/LeonardoDiCaprio had a very difficult time playing Dalton's roles as Dalton would, rather than how he himself would, especially since Dalton is supposed to be an actor of hidden range, so he suggested Dalton forgetting his lines mid-scene to ironically help him stay in character as Dalton. The following scene in the trailer was also unscripted.

* CreatorBacklash: Creator/BruceLee's daughter Shannon and Creator/KareemAbdulJabbar took great issue with Lee being portrayed as simply an ArrogantKungFuGuy with none of his deep philosophical thoughts on display, pointing out that Tarantino is far more respectful in treatment to other historical celebrities as compared to Lee.

** A heavy ActorAllusion with Creator/LeonardoDiCaprio, as Rick Dalton. Firstly, that he is a TV actor trying to break into film, which [=DiCaprio=] was successful with, whereas Rick is not at this point. Secondly he is cast to play a heavy in a Western, which is similar to his role as the FauxAffablyEvil Calvin Candie in ''Film/DjangoUnchained''. Lastly, him suggesting that he throw his young co-star is an allusion to [=DiCaprio=] cutting his hand in ''Django'' and incorporating it into the scene when he smeared his blood on Kerry Washington's face.

* RoleReprisal: An odd case with Creator/DamonHerriman, who reprises his role as Charles Manson from ''Series/{{Mindhunter}}'' -- he apparently auditioned for each role separately, and just happened to have been cast in both by coincidence. He plays the younger Charlie here; in ''Mindhunter'', he plays Manson after decades in prison.

** Creator/LukePerry is unfortunately died in March 2019,4 months before this film is released. However, he did complete filming all of his scenes and his scenes can be seen in completed film.

* ApprovalOfGod:
** Debra Tate was initially very apprehensive about the project as she feared the murder of her sister Sharon would be salaciously exploited (she's been defending her sister's memory against exploitation for decades), but after talking with Creator/QuentinTarantino and reading the script, she gave it her blessing. Debra also admitted that she wept when she saw Creator/MargotRobbie perform as Sharon, saying that Robbie nailed the role: "[[SugarWiki/HeartwarmingMoments I actually got to see my sister again nearly 50 years later]]."

** Completely averted with both Creator/BruceLee's daughter Shannon and Creator/KareemAbdulJabbar, who took great issue with Lee being portrayed as simply an ArrogantKungFuGuy with none of his deep philosophical thoughts on display, pointing out that Tarantino is far more respectful in treatment to other historical celebrities as compared to Lee.

* CastTheRunnerUp: Creator/BradPitt was reportedly in talks for an unspecified role in the film, which was rumored to be a detective investigating the murders, and was eventually turned down by Pitt. Negotiations stopped for a couple months as it was assumed Pitt wasn't interested. Creator/QuentinTarantino then tried to consider Creator/TomCruise for a role as many assume it was the same role (it has not been confirmed) that Pitt declined but matters never materialized with Cruise. Tarantino then went back to Pitt months later for a role again but this time, the role was confirmed for being the stuntman character, Cliff Booth, which Pitt would sign on to do.

* AcorInspiredElement: Creator/LeonardoDiCaprio had a very difficult time playing Dalton's roles as Dalton would, rather than how he himself would, especially since Dalton is supposed to be an actor of hidden range, so he suggested Dalton forgetting his lines mid-scene to ironically help him stay in character as Dalton. The following scene in the trailer was also unscripted.

* FakeAmerican: Australians Creator/MargotRobbie and Creator/DamonHerriman as Creator/SharonTate and UsefulNote/CharlesManson.

** Flowerchild taking the car keys and abandoning the other Family members. [[spoiler:Linda Kasabian, the person on whom Flower's based, was the only unwilling participant in the real-life Tate killings; she was unable to stop the others from going ahead with the plan, but she never went into the house or attacked anyone. When the case came to trial, Kasabian turned state's witness and told the jury everything she could recall about the Family and the murders.]]

* FakeAmerican: Australians Creator/MargotRobbie and Creator/DamonHerriman as Sharon Tate and Charles Manson.
FakeBrit: American Rumer Willis as English Joanna Pettet.

** As mentioned, Creator/BurtReynolds was originally intended to play George Spahn before his death. Creator/JamesMarsden was also intended to play a younger Reynolds, but his scenes were cut, perhaps because the CastingGag wouldn't work without Reynolds in the film.

* RoleReprisal: Notably averted by Creator/DamonHerriman, who reprises his role as Charles Manson from ''Series/{{Mindhunter}}'' -- he apparently auditioned for each role separately, and just happened to have been cast in both by coincidence. He plays the younger Charlie here; in ''Mindhunter'', he plays Manson after decades in prison.

** A heavy ActorAllusion with Creator/LeonardoDiCaprio, as Rick Dalton. Firstly, that he is a TV actor trying to break into film, which [=DiCaprio=] was successful with, whereas Rick is not at this point. Secondly he is cast to play a heavy in a Western, which is similar to his role as the FauxAffablyEvil Calvin Candie in Film/DjangoUnchained. Lastly, him suggesting that he throw his young co-star is an allusion to [=DiCaprio=] cutting his hand in Django Unchained and incorporating it into the scene when he smeared his blood on Kerry Washington's face.

* RoleReprisal: Creator/DamonHerriman reprises his role as Charles Manson from ''Series/{{Mindhunter}}''.

* ActorAllusion:
** Sharon Tate is introduced on a Pan-Am plane. ''Series/PanAm'' was Creator/MargotRobbie's breakout role outside her native Australia.

* FakeAmerican: Australian Creator/MargotRobbie as Sharon Tate.