Factual error: The show is set in the fifties but Fonzie has a Mustang hubcap on the wall of his garage. The first Mustang came out in 1964.
Continuity mistake: In Arnold's, throughout the series you can see the men's toilets on the left and the women's toilets on the right. But whenever Richie, Fonzie or any boy goes into the men's toilets, they make a right.
Factual error: When Arnold's is seen from the inside, metal pinball machines are seen. Since this show is set in the 50's, the pinball machines should be wooden. Metal pinball machines didn't show up until the 70's.
Suggested correction: Steel pinballs date back to the 1940s.
Factual error: The show takes place in Milwaukee, but several times palm trees are visible in the background. One blatant shot is over the wall at Arnold's.
Other mistake: The interior of the house (excluding the first season), has a door from the kitchen leading outside not far from the front door on the same side of the house and no windows facing that direction, but from the exterior of the house always shown, there is no 2nd door by the front door. Instead, a large window is shown where the kitchen door should be.
