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.
Answer: If all the actors and hands know their roles well enough they could perform the play reasonably well even without a director.
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