The character of Rhoda did not go over well, in early run-throughs before an audience (it was thought she was "too mean" to Mary), but after one line of dialogue was added, it gave audiences a whole new perspective. Phyllis responds to Mary's question ("who's Rhoda?"), "that dumb, awful girl who lives upstairs, that Bess likes". The addition of Bess's line, "Aunt Rhoda's really a lot of fun. Mom hates her". With Bess's simple line, one of the most iconic characters, as well as one of TV's most indelible, endurable and memorable friendships, was born.
The character of Ted Baxter was modeled on Jack Cassidy. He, in fact, was offered the role but did not accept (though, he does appear in one 1st-season episode, as Ted's brother, Hal Baxter).
At the initial read through, actor Angus Duncan so disliked the script, he threw it, and was almost fired on the spot. However, after the problems were worked out, and the pilot episode was shot, to very positive reviews from the audience, Duncan asked if his character could become semi-regular, to which Messers, Brooks and Burns said 'thanks, but no thanks'.
Gavin MacLeod originally read for the role of Lou Grant, but he did not want the part. In an interview with the Star Tribune in 2013, MacLeod said he preferred the role of Murray, so he read a few lines and left. His agent called him later to tell him he'd won the part.
Ed Asner, Gavin Macleod, Cloris Leachman, and Betty White all died in 2021.