Penny Marshall worked the milk and Pepsi joke in based on her own life because as a child her mother would fill the same cup with milk as later with Pepsi and often wouldn't rinse out the cup or even wait until it was empty.
Frustrated at TV shows constantly repeating who the characters are and what they do, Penny Marshall came up with the idea of Laverne having L's on all her clothes, figuring that would solve the problem. To her chagrin, they still had to say on a regular basis who was who and where the girls worked; she got tired of all the times Cindy Williams would say 'Laverne' in an episode.
Michael McKean and David L. Lander were originally hired as writers/consultants. They wrote themselves into the show as Lenny and Squiggy, two characters they created in college. Squiggy was originally named "Ant'ny" but the producers wanted the two boys' names to coincide with the girls'. Squiggy was the name of an unseen character in McKean and Lander's "Lenny and Ant'ny" sketches.
While still a defensive end with the L.A. Rams, actor Fred Dryer made his television debut in a 30 second spot as a lifeguard in Laverne's dream sequence in the 6th season premiere "Not Quite New York".
When Cindy Williams departed during the 1982-1983 season, due to pregnancy, her absence was explained by having Shirley moving out of the apartment to be with her husband Walter after he was transferred out of the country.