General Crook did really exist and he arrived in Deadwood with his troops. General George Crook led a military expedition in pursuit of a band of Sioux Indians who were fleeing after the Battle of Little Bighorn, in fear of retaliation. Crook and his troops, didn't have enough rations to last them for the length of time they were tracking the Indians. As a result, as one of their horses or mules went lame, they resorted to eat the meat. This was referred to as the Horsemeat March of 1876. Crook sent ahead Captain Anson Hills, with a small group of troops to request a train with supplies to meet them in Deadwood. Hills and his troops came across a Lakota war party but didn't have the numbers needed to defeat the Indians. Crook arrived in Deadwood, they were able to get their supplies but were still out numbered and worn out to defeat the Lakota.
The piano piece heard being played by the Gem's piano player at the end of the episode is an old minstrel song written in 1852 by Stephen Foster called "Massa's In The Cold, Cold Ground." The song bears many resemblances to Jay Ungar's "Ashokan Farewell" which served as the theme song for Ken Burns: The Civil War, and it is likely that Ungar drew inspiration from "Massa's In The Cold, Cold Ground" for his song.
This is the first episode that Molly Parker (Alma Garret) and Kim Dickens (Joanie Stubbs) have a scene together. They worked together again on House of Cards.