When Bart stands in the door of the saloon and verbally taunts Johnny, Johnny pauses a moment to listen. Behind Johnny, a hill between two buildings is shown. On that hill is a hydro pole with metal transformer box: this did not exist in 1867.
The show begins with Johnny's papers being blown in the wind, Punch holes can be seen in his papers. Punch holes also obvious in "Yellow Hair" when Santanta's daughter picks up Johnny's papers. According to Jess and Ned's tombstone, Johnny returned home a few weeks after his father's death in 1867. The first hole puncher, invented by Frederich Soennecken, was patented Nov. 14, 1886, almost 20 years after Ned Yuma's death.