The Grand Central Hotel—a three story, 64-room luxury hotel with steam heat and indoor bathrooms—was built in 1879 by Seth Bullock and his partner after the hardware store he co-owned with Sol Starr burned down. The Bullock Hotel continues to operate to this day as a casino.

E. B. Farnum was one of the first residents who was neither a miner nor prospector; he was the owner of a general store, not a hotel. He was married with three children when he arrived in Deadwood. He was very active in convincing the Dakota Territories to officially recognize the town and establish a nearby Army post, contrary to the series which had him oppose it under the sway of Al Swearengen.

Wild Bill Hickok's funeral was not, as the series suggests, a sparsely attended affair. Charlie Utter was away when Hickok was killed, but he returned and claimed the body. He placed an advertisement in the local paper and attended the funeral.

Gem Theater, referred to in the series as the Gem Saloon, was not built until April 7, 1877, the second of Al Swearengen's establishments. In 1876 when Bullock and Star arrived, Swearengen ran a small establishment called the Cricket Saloon, which featured bare-knuckle boxing among miners, as well as dog fights and cock fights.

Charlie Utter was unlike the show's somewhat unkempt man, uncomfortable in urban settings. He was known for the pride that he took in his appearance. He dressed in hand-tailored suits and kept his long blonde hair and mustache well-groomed at all times, keeping combs and mirrors with him constantly.

Seth Bullock was not married to his brother's widow, but to the woman who was reportedly his childhood sweetheart, Martha, whom he married in Utah in 1874. Robert Bullock was not Seth's brother, but a cousin. He did not have a son at the time when his wife came to join him, but a daughter, Margaret, who was still just a toddler. They subsequently had another daughter, Florence, and a son, Stanley. He deputized several people while sheriff, but not Charlie Utter. He was from Amherstburg (in Canada West at the time of his birth, but Ontario at the time of the storyline), and not Etobicoke as depicted in the series.

Al Swearengen was not originally from England, but Iowa. At the time the story opens in 1876, he was still operating the smaller Cricket Saloon. He was also still married to Nettie Swearengen, his first wife (but in keeping with his fictional counterpart, she divorced him on the grounds of mistreatment some time later).

Jane Canary is never referred to her by her nickname "Calamity Jane," though by 1876 she herself had not used anything but her nickname for several years. The show does not make clear that she did not become friends with Hickok and Utter until after they had been in Deadwood for some time. After arriving in Deadwood, she stopped wearing men's clothing, and worked for Swearengen at the Gem Theatre.