Anachronisms: Episode 1: A portion of blacktop highway and guard railing is visible behind Hickock's wagon as it descends the hill into Deadwood.
Anachronisms: At one point, Starr tells Bullock: "Your fly is down". In 1876, trousers had buttons, not zippers. Bullock's fly would have been "open" or "closed", not "up" or "down".
Factual errors: The series shows Seth Bullock and Sol Starr witness Wild Bill Hickok's arrival in Deadwood, however in reality, Wild Bill arrived in Deadwood two weeks prior to Bullock. Bullock arrived in Deadwood on 1 August 1876, the day before Bill was killed by Jack McCall.
Anachronisms: In one scene set in the Gem Saloon, the tune to "Waiting for the Robert E. Lee" is played on the piano. This song was composed in 1912, and the show is set in 1876-77.