Shirley Douglas couldn't portray herself onscreen because in a previous Corner Gas episode she played a woman who had a fling with Oscar.
Final appearance of Mike O'Brien as Wes Humboldt. This was the only episode O'Brien appeared in for Season 5, a fact that may have been alluded to in the script when Hank tells Wes "I thought you died or moved to Winnipeg or something" and Wes responds "Nope, I've always been here. You guys just didn't seem too interested in calling me." Hank's comment turned out to be sadly prophetic, as O'Brien passed away from cancer in Winnipeg in 2015.
Brent bought a bottle of 20 year old Scotch and figured it would be 40 year old Scotch after keeping it for 20 years. As far as whiskey goes, it only ages while in the barrel. The time in the barrel strongly influences the flavor; the time in the bottle does not count.