Corrected entry: The guys sing "O Canada". They sing the line "From far and wide, O Canada". This line wasn't added until 1981.
Corrected entry: While at the mountie station, at one point Kelso is standing in front of a map of Canada, with Nunavit drawn on it. Nunavit was created in 1999 by splitting Northwest Territories in half, and would not have been shown on a map in the '70s.
Correction: Nunavit was drawn on it, but unless it actually says Nunavit on the map it's not wrong, because on older maps they have always denoted the boundary between both the Northwest Territories.
Nunavut borders were set in 1993, and territory was separated in 1999. Those borders didn't exist in any form before that.
Correction: Although "O Canada" was not adopted as the Canadian National Anthem until June 27, 1980, the words are in keeping with the history of the time. The Weir version had the line "Stand and guard, O Canada" until it was recommended by a Special Joint Committed in March 1967 that the line be changed to "From far and wide, O Canada." The change was adopted in 1967 and it took Canada several years to work out the copyright issues. However, the line was common to the song as of the mid 70s and would probably have been the only version known by teenagers from Wisconsin.
Zwn Annwn