Moon Over Point Place (1) - S2-E26
Continuity mistake: Red, Kitty and Midge are talking to Bob about Eric and Donna having sex. Red makes a point and Midge turns her head to look at Bob. The shot cuts and we see her from the side, repeating the head turn.
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