- Actor-Inspired Element: The show's version of Al Swearengen being born in Britain was a ploy by the show to excuse any potential lapses in Al's American accent caused by Ian McShane being a Brit; the real Swearengen was born in Iowa to a Dutch family.
- Author Existence Failure: Powers Boothe passed away in 2017, shortly after the script for the film was completed.
- Cast the Runner-Up:
- Powers Boothe was originally cast as Al Swearengen. But Boothe fell ill before the pilot was to start filming. Boothe was replaced by Ian McShane, and then was given the supporting role of Cy Tolliver.
- Garret Dillahunt pursued the role of Seth Bullock, but Timothy Olyphant was already cast. The only role that was available at the time, was of Doc Cochran, so Dillahunt auditioned for that. He played the recurring role of Jack McCall in season one. Dillahunt was then considered for the role of George Hearst in season two, but it was decided that Hearst would not appear on-screen until the season finale. Dillahunt played the recurring role of Hearst's employee, Francis Wolcott.
- Paula Malcomson (Trixie) initially auditioned to play Alma Garrett and W. Earl Brown (Dan Dority) pursued the role of Jack McCall.
- Dawson Casting: While Wild Bill Hickok was 39 years old when he died, Keith Carradine, who plays him, was 55 years old at the time this series was produced. This might be a case of Age Lift, as was done with Al Swearengen.
- Disabled Character, Disabled Actor: Geri Jewell, who plays Jewel, actually has cerebral palsy.
- Dyeing for Your Art: Keith Carradine was grateful that he had time to grow a real mustache for his role as Wild Bill Hickok, thus sparing him the hassle of gluing on a fake one every day.
- Enforced Method Acting: Keith Carradine had to wear blue contact lenses to simulate Hickok's eye color. Ultimately this helped his performance. The contacts hurt his eyes, and helped him achieve Hickok's perpetual foul mood.
- Playing Against Type:
- Brad Dourif, known for a long and colorful career of playing almost entirely creeps, perverts, crooks, murderers, and assorted psychopaths, plays the asexual town doctor, one of the few gallant and honorable men in a town full of creeps, perverts, crooks, murderers, and assorted psychopaths.
- Kristen Bell, who usually plays goofy cute girls, plays Flora, a duplicitous, knife-wielding sociopathic Fille Fatale.
- Real-Life Relative: Three actors had adult children cast in minor roles as prostitutes. Parisse Boothe, the daughter of Powers Boothe, played Bella Union prostitute Tess in five episodes, and Fiona Dourif, the daughter of Brad Dourif, appeared in three episodes as the "Chez Ami Whore". Cade Carradine, son of Keith Carradine, played a prospector named Jubal in "Complications".
- Troubled Production: The show became legendary for its behind the scenes trouble:
- It was the most expensive regular series aired at the time, with the budget being $6 million an episode, largely dedicated to authentically recreating the titular Old West town, with interiors and exteriors functioning as elaborate, stage play-like sets, including lighting that could recreate the sun's position for a certain time of day. As such, it's the rare HBO series that's co-owned by another studio (Paramount Television).
- Then there were problems with Creator/Showrunner David Milch, whose wildly unconventional style relied heavily on combining Purple Prose and Writing by the Seat of Your Pants. Actors spoke of only having a few minutes to rehearse Milch's extremely difficult, almost Shakespearean dialogue he wrote or rewrote just before the fact.
- Beyond that, sequences and even entire episodes were left on the cutting room floor due to Milch's displeasure with them, with Milch even admitting that much of the third season had been reshot.
- All these factors led to HBO canceling the series after its third season, and The Movie meant to tie up loose ends being mired in Development Hell.
- In 2017, fans suddenly got real reason to hope for the movie again as multiple sources claimed the script was complete. Then Powers Boothe died, which further delayed the production.
- Shortly before the movie was finally released in 2019, Milch revealed that he'd been suffering from progressive Alzheimer's Disease for the past few years, which forced him to mostly leave the production alone after turning in his script in stark contrast to his usual extremely hands-on production style.
- What Could Have Been:
- At one point, David Fincher was set to direct the pilot.
- The role of Al Swearengen was originally written for Ed O'Neill. O'Neill screen tested for the role but HBO executives did not want to cast him because of his fame as Al Bundy. O'Neil would eventually get cast in Milch's followup series, John from Cincinnati.
- John Milius tried to get a job as a staff writer; showrunner David Milch was reluctant as he did not consider Milius a staff writer. Milius pleaded that he needed the money in order to pay for his son's tuition at law school, so Milch simply paid the fees.
- The really big one: Milchs original idea was to make a show about the creation of the Roman Empire, only to find out HBO was already developing a show set in Ancient Rome. This set him looking for another era that could retain the spirit of a civilization being built from the ground up, and he settled on the Old West. The gladiator-style brawl between Dan and Turner, with both looking up to their employer on a balcony for permission to kill, may be a nod to the original idea.
- You Look Familiar: Garret Dillahunt played the coward Jack McCall on the first season of Deadwood, then came back the next season to play murderous psychopath Francis Wolcott. McCall has a drooping eyelid and Wolcott has a full beard, lessening the facial similarity between the two. Dillahunt has since been predominantly typecast as either slack-jawed yokels like McCall or seething psychopaths like Wolcott. In 2019, Dillahunt came back for an uncredited cameo in the movie.
Trivia / Deadwood