Punk Chick - S1-E22
Revealing mistake: While cuddling in the car Donna tells her boyfriend that she isn't wearing a bra when it is obvious that she is - at one stage when she leans toward him her sweater tightens across her back and the shoulder strap and clasp of her bra is outlined.
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