When this episode originally aired, it was the first one after Mary, Lou, Murray, and Phyllis had returned from New York City for Rhoda's wedding. That episode of Rhoda (1974) was one of the most-watched TV shows in television history.
Phyllis tells Mary she is 43 years old. In reality, Cloris Leachman was 48 years of age when the episode originally aired.
This is the second episode (after Bess, You Is My Daughter Now (1970)) the viewers see any part off Phyllis' apartment. She, husband Lars, and daughter Bess had the entire first floor of the Victorian house, while the second floor (which appears in the credits to be just as large as the first) was another apartment. Aside from the perennial question, long-time fans have as to where Rhoda's apartment was located, Mary's apartment is '#4', so the 2nd fl. must have been divided (viewers got to meet the 2nd floor. tenant only once; when she asked Mary for boxes, saying she worked).
This is the fewest number of main castmembers (4 - Mary Tyler Moore, Edward Asner, Gavin MacLeod, & Ted Knight) that appear in an episode during the show's run.