When Harry is in the cabin with the painter he is asked what year it is. Harry answers 1900. Shortly thereafter Harry says that Black Jack Ketchum was decapitated when hanged. Ketchum was hanged over a year after the time frame of this conversation, on April 26, 1901.
At 1:02 Harry Tracy is pasting US paper money on a wall, only the Federal Reserve Notes are from 1913 at the earliest. A $1 note from 1923 is also visible. Harry Tracy died in 1902.
The "trolley" Harry chases has no trolley pole nor overhead electric wire.
The headline on the newspaper Harry Tracy reads, announcing Merrill's betrayal, misspells the words "Pursue" and "Trail." It reads "150 Men Persue Bloody Tracy Trial." Surely they weren't talking about 150 newspapermen in a courtroom.