Continuity mistake: When Hyde enters the scene, his shirt is somewhat tucked behind his belt. In the following close-up shot his shirt is above the belt but returns to the tucked position in the next shot. (00:00:10)
Factual error: Fez wears a Sergio Valente pullover, which is a company not founded until 1981. (00:02:20)
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