Sabrina: The Animated Series S01 E52 Witchery Science Theatre

Sabrina gets a bad haircut and to hide it from Harvey she decides to go to the movies. The movie they originally wanted was sold out so she cast a spell and she, Chloe, and Harvey get transported in an old 50's movie. There Sabrina learns that it doesen't matter what you look like on the outside it's what counts on the inside.