In the scene where Paladin escapes the jail, the large, hulking prisoner O'Connor twists the bars out of the small cell window with brute strength alone. Gene Roddenberry, who wrote this episode, would use a variant of this in the Star Trek episode The Omega Glory (1968) where large, hulking prisoner Cloud William does the same with Kirk.
From the dialogue, this episode can be dated as occurring in mid May 1872. Paladin says "last week the Liberal Republicans nominated Greeley for President and Brown for VIce-President". This happened May 1-3, 1872 in Cincinnati.
The date of May 1872 established but the weapon Paladin carries is an 1873 cavalry model Colt Single Action Army. This weapon had yet to reach the market that early.