Mary Tyler Moore and Pippa Scott were married on screen to Dick Van Dyke. Moore on The Dick Van Dyke Show and Scott in the film Cold Turkey.
Jay Sandrich (director) and Pippa Scott (guest star) are, respectively, the children of film director Mark Sandrich and screenwriter Allan Scott, who worked on 10 projects together, among them four Astaire-Rogers movies.
According to this episode Mary is a 1959 graduate of Leif Erickson High, located in the (fictional) town of Roseburg in upstate Minnesota. She was a Viking Queen.
Richard Schaal, whose character Howard Arnell proposes to Mary Richards at the high school reunion, was at the time the real-life husband of Valerie Harper, whose character Rhoda Morgenstern joined Mary at the reunion. Rhoda was not in the scene, but Harper - who first met Mary Tyler Moore in 1966 on the set of The Dick Van Dyke Show, during an episode in which Schall appeared - was almost certainly on the set.
Mary tells Rhoda that she graduated high school in 1959. In real life Mary Tyler Moore graduated high school in 1955.