Because he is constantly exercising, Chachi (Scott Baio) refers to Fonzie (Henry Winkler) as Jack Lalanne. Francois Henri " Jack" Lalanne (September 26, 1914 - January 23, 2011) was a fitness and healthy diet advocate who had a fitness television show that ran from 1951-1985 (syndicated 1959-1985). He performed such feats as completing 1,033 push-ups in 23 minutes, on another show did 1,000 jumping jacks and 1,000 chin-ups in 1 hour 22 minutes. Jack Lalanne was in his forties when accomplishing these feats, but was actively performing other feats, such as swimming great distances while pulling/towing objects into his sixties and seventies.
Rita Wilson (Barbara) is married to Tom Hanks who made a guest appearance in the previous season. However they weren't married at the time, the two didn't marry until 1988.
This episode aired on the late Erin Moran's 23rd birthday (born 10-18-1960).