Nicholas Colasanto died two days after this episode was filmed. Production was shut down for three weeks as the cast and crew mourned and scripts were re-written. For the rest of the season, different explanations were given for Coach's absence.
Other than Season Three's final episode where they repeated a cold open with Coach from earlier in the season, this is the final appearance of Coach (Nicholas Colasanto) on Cheers as being a member of the ensemble moving the story along.
Diane says she'll think of Sam as Albert Schweitzer, an Alsatian-German (modern-day France) polymath (theologian, musicologist, humanitarian, philosopher, physician, and writer) and winner of the Nobel Peace Prize.