When Paladin asks Quill if he remembers the last time they met - at a bar in Buffalo, North Dakota, Quill responds that it was 'September 1872 - three years ago''. However, the first settlement for Buffalo was established in 1878 - six years after the incident supposedly happened.
Paladin is called by the name "Paladin" (without a first name) in most episodes, but is called "Harry" by his client when they first see one another.
One of the few - if not the ONLY - times where Paladin encounters an illiterate old man in the Old West. In reality, many settlers in the 1870s couldn't read or write, and notaries public made a tidy living witnessing peoples' marks on legal documents. In HGWT, however, almost every Westerner seemed educated to one degree or another. Here, Eph Trager (Raymond Hatton) looks at Paladin's credentials and merely says "looks like a business card" showing no knowledge whatever of what it means.