Continuity mistake: When Donna sees Eric in the driveway, and they apologize to each other, her two braids have a mind of their own as they move up, down, and every which way, as she and Forman speak.
Roller Disco - S3-E5
Revealing mistake: When Jackie and Fez are doing their Roller Disco routine, it becomes very obvious that doubles are used for many of the routines. Fez does a lot of his own stunts but Jackie does very few. While they do a decent job of hiding the stunt doubles, there are several times when you can see the faces of the doubles and it is obvious it is not Mila Kunis or Wilmer Valderrama. And you do not need slow motion or stop action to see the difference. (00:11:10)
Revealing mistake: Hyde claims he's reading a Mad Magazine spoof of Smokey and The Bandit. Look closely at the issue, and he's actually reading a spoof of the movie Dog Day Afternoon. That and Mad Magazine didn't make any parody of Smokey and The Bandit.
Factual error: When Mrs. Foreman gives Fez and Hyde Snack-Packs after they are caught trying to steal beer, they are in clear plastic containers. From 1968-1984, Snack Packs were in cardboard containers with a tin bottom and a tin pop top. From 1984-1990 they were in plastic containers, but not clear ones. It was not until 1990 that Hunts introduced the clear plastic containers.
Eric's Drunken Tattoo - S3-E22
Revealing mistake: In the scene where Eric tries to kick Donna's door open. When he does, he falls back and hits the wall behind him, which wobbles.
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)
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)
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