Very often Buffy was shown with her 'Mrs. Beasley' doll. That became the highlight of the show so much a line of replica Mrs. Beasley dolls was launched. It sold well and continued to sell even two years after the series' cancellation.
Producer Don Fedderson insisted that the character of Buffy remain perpetually six years old, even as Anissa Jones, the actress playing her, grew into her teens; in promotional appearances Jones was still required to bind her chest and carry the Mrs. Beasley doll.
When Sebastian Cabot unexpectedly became ill during the first season, he was replaced by John Williams. It was explained that Giles French was summoned to England by the Queen, and his brother Niles filled in at the Davis' doorstep.
Even though the series was still relatively popular during its final season, it still was canceled as part of the infamous "Rural Purge" when CBS decided to cancel all of their rural and family oriented shows in favor of edgier programming.
The French-dubbed version made in Paris had changes for the characters' first names. Though Brian Keith's "Uncle Bill" remained unchanged (and was part of the French version's TV title), the children would be renamed: Fanfan (Buffy), Jacky (Jody) and Cecile (Cissy). Mr. French's name would be also be changed to the friendly name of "Mr.Felix".
The series had a 60 day production schedule. However, Brian Keith would film his scenes in 30 day blocks, much like how Fred MacMurray did while filming My Three Sons (1960). That meant that the other actors would film their scenes around his. This was done in order to free Keith for any film roles that might come up.
Interestingly, the show was set in the same television "universe" as My Three Sons (1960) and To Rome with Love (1969) due to the fact that all three shows were produced by the same production company. In fact, the characters of Mr. French, Buffy and Jody made a crossover appearance on "To Rome with Love". Ironically, none of the cast from "Family Affair" ever appeared on "My Three Sons".