Coach's absence is explained by his being in Ohio for a family reunion; not, however, his own family's reunion.
Alison LaPlaca is married to Philip Charles Mackenzie, who played the obnoxious fiancé of Coach's daughter in a first season episode.
The bar regulars create a mash-up of several traditions as Sam changes the beer keg. They hum "Taps," a traditional funerary music in various militaries, as the dry keg is wheeled out. The proclamation of "The keg is dead! Long live the keg!" is a parody of a traditional proclamation that follows the death of a king in several European nations. "Hail to the Chief" is an American song that is traditionally played to introduce the President.
Ted Danson and Rhea Perlman are visibly emotional when discussing Coach, especially when Sam reads the line about giving Coach's love to everyone at Cheers.