Sheriff Mort Metzger makes the statement that Ron Stiller is no Tom Selleck. He appeared 3 seasons earlier in the cross over episode Magnum on Ice (1986).
The home of Bud and Lois Fricksey and the home featured in the TV series Growing Pains (1985) are one and the same. (There's a brief shot of the exterior at about the 20-minute-mark.)
The title refers to a term used by the United States' Postal Service for a letter that cannot be delivered due to the illegibility or absence of a forwarding or return address.
Imagine Jonathan Goldsmith, the actor who portrays Bud Fricksey, a little older and hairier and you might recognize him as The Most Interesting Man In The World character from the Dos Equis beer commercials.