This was the first episode of the series to be made, though not the first to air.
Based on the March 1953 "Uncle Scrooge" comic book of the same name.
The Klondike Gold Rush occurred in the late 1890s. As Scrooge is a young man (duck) in the episode during the gold rush, that would make him around 100 years old when he tells his nephews the story of his youth.