Beverly Garland (Barbara) was the first cast member to marry into the Douglas family without having made a previous appearance in the series. Tina Cole (Katie), who married Robbie (Don Grady) and Ronne Troup (Polly), who married Chip (Stanley Livingston), had both appeared in the series previously; Tina as a friend of Robbie's, and Ronne as an extra in a couple of classroom scenes.
Steve tells Millicent that his birthday is "near the end of August". Fred MacMurray was born on August 30, 1908.
In 1979 Tina Cole married Fillmore Pajeau Crank, Jr., Beverly Garland's son.