Factual error: A map of Canada appears behind the guys as they're being questioned by the Mounties. The territory of Nunavut, which was not officially drawn until the year 2000, appears on the map. It definitely did not exist in 1978. (00:18:45)
Factual error: The city of Winnipeg is spelled incorrectly on a road sign that appears while they are at the border, spelled 'Winnepeg'. (00:09:35 - 00:10:10)
Continuity mistake: Aston Kutcher slides out behind the car and screams in excitement while blowing an air horn. When he does, the wind messes up the front of his hair. A few shots later, it's neatly combed again.
Chosen answer: He isn't. Time moves slowly in the show because they didn't want it to turn into "That '80's Show". In the first episode, he say's he's 17 but the second episode was his 17th birthday so he must have been 16. The first 12 episodes are set in 1976, the next 2 seasons are set in 1977, the next 3 seasons are set in 1978, and the remaining shows take place in 1979 with the final show on Dec 31, 1979 when Eric must be 20 as he turned 17 in 1976.
Myridon