Continuity mistake: When Richie gets up from a table at Arnold's to meet with the Fonz in the men's room he's wearing jeans. When he enters the men's room he's wearing grey slacks. (00:07:50)
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.
Continuity mistake: In this episode, Fonzie has to go to the hospital to get his tonsils removed. In season 2 episode 6 "Haunted" Fonzie stated that he had his tonsils removed when he was a kid.
Marion: Fairy Godmother - S6-E21
Continuity mistake: Ralph is at Al's after everyone else has left on their dates. He's depressed and as he walks up to a table, you can see a couple of plates of food sitting on it. Then Fonzie comes in (hitting the wall to turn the lights on) and Ralph looks away from the table (he doesn't move otherwise). Then they show the table again - which is completely empty.
Continuity mistake: There is a blizzard on Christmas Eve dumping two feet of snow on Milwaukee. Mrs. Cunningham, LaurieBeth and Al are stuck at the Cunningham's house. Near the beginning of the episode, they show an exterior shot before they go inside the house. The driveway for the house is wet looking but totally clear of snow, with no one there to clean it, and it's still snowing. The hardware store has two feet of snow outside of it.
Continuity mistake: A pilot takes Chachi up in a small plane so Chachi can go skydiving. In the long shots showing a real airplane in flight, the sky is deep blue and cloudless. In the close-ups, filmed in a studio, the plane flies through several wispy clouds, likely formed by a wind machine blowing the mist rising from dry ice.
Answer: When it was originally broadcast there was a different ending. A new ending was added when the show was rerun to set up the Mork and Mindy series.