Even though this was show number eight of the series, this was the third show filmed.
In this show it is learned that Mark's middle name is 'Warren'. When he is at the bank, the banker is filling out paperwork and says "Mark Warren".
While the company that became Wrangler was begun in 1904 Wrangler jeans themselves did not appear on the market until 1947 so the previous contributor is not quite correct.
When John Harlan gives his speech at the bank he has a distinct Irish accent. In later episodes the accent is completely gone.
The Rifleman is filmed for the 1880's time period. Lucas McCain is wearing Wrangler jeans that weren't invented until 1904