Carla's shirt pattern is a miniature silhouette of Charlie Chaplin's famous character "The Tramp".
It is revealed by Frasier that his mother (played by Nancy Marchand in season three) has died. In the spinoff series Frasier (1993) his mother will be played in a flashback by Rita Wilson.
A notice (or certificate) is now hanging on the back bar post
Frasier quotes a lyric from the song "Everybody Have Fun Tonight," by the new wave band Wang Chung. The term "wang chung" is Chinese for "yellow bell" and is also used as the name of the first note on the Chinese musical scale. Basically, it means nothing.