Though Barbara Anderson and Elizabeth Baur both worked on the series Ironside (1967), they never appeared together since Elizabeth Baur replaced Barbara Anderson. This situation is unique in TV reunion movies since the original series cast is usually used in lieu of replacement actors who join later in the series.
Even though Raymond Burr's characters Perry Mason and Robert Ironside are in different series and have no relation to each other, both had moved to Denver, Colorado at the time of their reunion movies which was the location that Raymond Burr preferred to work in.
Katherine Ironside was a replacement for the character of the Comissioner in the original series, as Gene Lyons, the actor who had portrayed him, died in 1974. She is given the distinction of being hailed by Ironside at his retirement party at the beginning of the film, even though she hadn't yet been created at the time of the original series. In fact, Ironside was unmarried during the run of the original series and living in a bachelor pad.