Factual error: One of the rifles used in the game is a Winchester high wall. The game is set in 1880 and the high wall didn't come out until 1885.
Factual error: One of the mini games played in the Saloon is Texas Hold Em. The game is set in 1880, Texas Hold Em wasn't played until 1900.
Other mistake: When Clay and Colton are on the train going to the mining fort, they begin to shovel coal into the furnace to make the train go faster. They dig their shovels into the coal, the sound of coal getting scooped is heard, but when they move the shovel from the coal holder to the furnace, there is not one bit of coal on the shovels.