criterionforum.org

This reads a lot like Boogie Nights, and the parallels between the two film's historical contexts are fairly obvious (with the end of the Golden Age of Porn being substituted for the late silent and early sound era), but without saying too much I'd suggest that Babylon's is a far more cynical and perhaps even iconoclastic script. Certainly the Anger reference is more than coincidental (a lot more), though there isn't too much in the way of cribbing actual stories from Anger's book (though Clara Bow's, Erich Von Stroheim's, and a few others are present). On that note, the above description of Babylon as a big-budget NC-17 film is entirely appropriate. Though I'm sure it will be cut down before filming (both for content and because the script is almost 200 pages long), the script as I've read it is the most explicit thing I've ever seen from a big American studio (as in, Wolf Of Wall Street levels of swearing and quite a few graphic sex scenes, two of which are among the most bizarre I've ever read).

A word on casting: The film has a lot of parts, with fictional characters intermingled with historical figures, but there are three main roles: Emma Stone as Clara Bow, Brad Pitt as Jack Conrad, a fictional established movie star based on John Gilbert (they haven't announced what role Pitt is playing yet, but the descriptions of Conrad's character makes it unambiguous), and the as-yet uncast role of a fictional young Hispanic man, Manny Torres, who becomes a studio fixer and gets dragged into the wild personal lives of the other leads.

Sidney

seedy characters, Hollywood setting, transition to sound, ambitious climbers, crime scenarios, debauchery

To recap:

Margot Robbie: Clara Bow
Brad Pitt: Fictional, John Gilbert-inspired movie star Jack Conrad
Diego Calva: Fictional studio fixer Manuel "Manny" Torres
Jovan Adepo: Fictional jazz trumpeter Sidney Palmer
Li Jun Li: Anna May Wong

Katherine Waterston's part hasn't been announced yet, but unless the script has been massively revised, I'll guess that she is Elinor Glyn. Flea, Roberts, Scovel, Byrne, and Haas are presumably the collection of producers, moneymen, and studio-hangers-on that make up most of the film's male supporting parts (I'd wager right now that Haas is going to play small-time drug dealer The Count). Not sure who Samara Weaving is playing, but there's a good chance that it's Colleen Moore, and whoever Damon Gupton is playing is not in the leaked script (though I'm guessing he was cast in part because he can play trombone). There's still one supporting part (Zora) that unambiguously has not had an actor announced for her yet, so I'm interested to hear about that.

Wait, this takes place in the 50s now?

A very small bit; just a few minutes. The overwhelming majority takes place in the years 1926-1930. Any more than that about the 50s segment would give the game away about what is being done with it.

I was told by someone that this is actually the set for the new Spielberg autobiographical film. The time period and the choice of a (mediocre) De Mille in my mind makes me feel that’s the right answer.

The 50s segment is specifically stated to be set in the winter/spring of 1952, the year of The Greatest Show on Earth's LA premiere. I'd be very surprised if both films specifically referenced this exact same point in time.