During the first few episodes of the first season, Jeff and Suzie's child Sammy is referred to as a he; in later seasons she is a girl.
Larry and Cheryl mention having several kids in this episode, even though they are never seen. In the series they never mention having children and, obviously, they're never seen.
Richard Lewis tells Larry that his girlfriend speaks seven languages. Sofia Milos, who plays the girlfriend, does speak seven languages, according to her IMDB bio.
The fictional movie "A Hard Nut To Crack" starring Dustin Hoffman is actually the title of the original Die Hard (1988) film starring Bruce Willis in some foreign language overseas markets.