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.
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 aluminum containers. From 1984-1990 they were in plastic containers, but not clear ones. It was not until 1990 that Hunts introduced the clear plastic containers.