- Acting for Two: Fred MacMurray played both Steve and a Scottish relative of Steve's in "Scotch Broth" and the four-part arc that opened the final season.
- Don Grady played Robbie and a Robbie lookalike in "The Wrong Robbie".
- Channel Hop: From ABC to CBS in the fifth season.
- He Also Did: Don Grady was a talented musician who pursued a music career while still on the show. Using the pseudonym Luke R. Yoo, he was the drummer for the band Yellow Balloon, who reached the Top 25 in 1967 with a song entitled "Yellow Balloon" (the flip side of the single was the song played backwards!). Later on, he cut an album for Elektra Records under his real name of Don Aggrati, and later composed the theme music for Phil Donahue's talk show.
- Missing Episode: Averted. But with 380 episodes, two rerun packages were made of the show. The first (and most popular) consists of the 1965-1970 color episodes, spanning the sixth through midway through the 11th seasons. The other package has the first five seasons (1960-1965, all black-and-white) and the final 1 1/2 seasons (the second half of the 1970-1971 and the full 1971-1972 seasons). To those unfamiliar with the workings of syndication, the shows that aren't part of the package currently shown on cable or their particular local station might conclude the other episodes are either missing or lost.
- Money, Dear Boy: By the time the series was offered to Fred MacMurray, his movie career was slowing down and he took the role primarily for the steady paycheck. He also negotiated a clause into his contract where he'd only be available for the first 65 shooting days of the season, giving him plenty of time offnote while everyone else had to work around his absence.
- Real-Life Relative: An odd case: Brothers Chip and Ernie Douglas, played by real-life brothers Stanley and Barry Livingston, aren't supposed to be blood-related. Ernie was introduced as a younger friend of Chip's and was later adopted into the Douglas family.
- Real Life Writes the Plot: Tim Considine clashed with executive producer Don Fedderson and chafed at being contractually forbidden from motor racing. This led to his departure and Mike being written out of the show.
- Recast as a Regular: Tina Cole showed up as various Girl of the Week for Robbie a few times before being cast as Katie.
- Romance on the Set: Tim Considine and Meredith MacRae dated in real life while they were on the show while Don Grady and Tina Cole almost got married in real life. They broke up shortly before Grady left the show.
- Working Title: The show was originally going to be named The Fred MacMurray Show, but Fred MacMurray didn't like the idea.
- Written by Cast Member: Tim Considine (Mike) and Don Grady (Robbie) each co-wrote two episodes. Considine wrote "Goodbye Again" and "The System", while Grady wrote "Tramp and the Prince" and "First, You're a Tadpole."
Trivia / My Three Sons