Once Upon A Time In Hollywood Movie Facts, Easter Eggs and hidden details

This scene (top) from 'Bounty Law' in Once Upon a Time in Hollywood (2019) is filmed on the same location in Melody Ranch, as the scene (below) from Django Unchained (2013).

Sharon Tate and friends enter the restaurant through the exit lane and park. I found this interesting since it implies a certain self-superiority these people have for themselves.

When Rick Dalton goes to Italy to make spaghetti westerns, the narrator states the movie he worked on was directed by Antonio Margheriti. A callback to Donny Donowitz's alias when going undercover in Inglorious Basterds (2009)

Tarantino intenionally mismatched the name at the start of the movie

Dalton's Lancer character name is an acronym

Brandy, Brad Pitt's pitt bull was portrayed as a female, however in the climactic home invasion scene she was played by a male dog.

Just before talking to Sam Wanamaker about his role on "Lancer", Rick Dalton has his face down in a bowl of ice water. This is a beauty treatment supposedly started by Joan Crawford, to "reduce puffiness" around the eyes, after a long night of drinking.

When Bruce Lee jump kicks Cliff Booth, there were many extras in the background as witnesses. Thereafter, when Booth throws Lee into a car and spars with him over a few punches, the extras are gone.

When Cliff smokes the Acid Dipped cigarette and hes making the dog food, you can hear a faint distorted wobbling noise when he waves his hands around.

During Rick Dalton's western shoot in Once Upon a Time in Hollywood (2019), Timothy Olyphant's character rides a horse through town. The camera pans left with a wooden fencing structure at the foreground flipping by, as if simulating a classical rolling film reel.

keeping with the Western themes in Once Upon a Time in Hollywood (2019), when Brad Pitt arrives at the Manson ranch, his laces are tied to the sides of his moccasins and he jingles his keys as he walks...meant to evoke the spurs of a dangerous stranger entering town in a cowboy flick.

In the scene where Leonardo Di Caprio uses the flamethrower for the first time, you can see the actors playing the Nazis wearing a fireproof suit right after the flames are thrown.

Rick Dalton is reading a book about a 'bronco buster'. When Cliff Booth enters Spahn's house at the hippie infested ranch, this sculpture can be seen inside. It is 'The Bronco Buster' by Frederic Remington.

When Cliff is visiting George Spahn's house, you can fairly hear the song "Snoopy VS The Red Baron" playing on the radio in the background. This is the exact same song that Rick is listening to in the pool at the end of the film.

Damon Herriman, who portrays Manson in Once Upon A Time In Hollywood (2019), also portrays him in Mindhunter Season 2.

The poster of the fourth spaghetti-movie "Operazione Dyn-o-mite!" is directed by Antonio Margheriti, which comes from the infamous Italian scene in Tarantino's other movie, Inglorious Bastards (2009).

Rick Dalton sings the 1956 Jim Lowe hit The Green Door. "Wish they'd let me in so I could find out, What's behind the green door". No one knows the meaning behind the song but in the Tarantino universe there is a green door in Pulp Fiction.

Brad Pitts' and Leonardo DiCaprio's names are on each other because Pitt's Character is DiCaprio's Stunt Double.

We are very subtly given the answer to the mystery of what really happened to Cliff's wife. More explanation in comments.

When DiCaprio is playing the antagonist of the TV show Lancer, his co-star says "lead the way, Monsieur Dakota." This is a nod to Tarantino's earlier work, "Django Unchained" (2012) where DiCaprio plays the antagonist and insists everyone call him "Monsieur"