The Night of the Vicious Valentine - S2-E20
Factual error: Artemus opens a cabinet to reveal a map of the United States where he and West are keeping track of the alphabetical murders. The map is far out of date for the Grant administration, with what became the state of West Virginia during the Civil War still part of Virginia, and missing entirely the states of Nevada, Oregon, Kansas, Nebraska, and Minnesota-all of which were part of the union before President Grant took office. (00:04:45 - 00:06:30)