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.
Penny Marshall has said her favorite episode is "Why Did The Fireman?...," one of the few very serious episodes on the show. The plot has Laverne's boyfriend Randy (played by Ted Danson) dying while fighting a fire. Laverne becomes depressed and goes into denial, and then her father has to talk her out of it.
Various Happy Days cast members have talked about the vicious fights next door on set of Laverne and Shirley, so loud that they would listen with glasses to the wall.
After The Odd Couple (1970) ceased production, the apartment set on that show was modified to become Laverne and Shirley's apartment.
For several years there was a certain amount of interplay between the characters of this show and Happy Days (1974), especially when both shows were set in Milwaukee, Wisconsin.