The TV series:
- Acting for Two: Robert Culp as Kelly and the General in "The Warlord".
- Actor Allusion: In "Little Boy Lost" Scott talks about childhood friends including Weird Harold, imortalized both in Cosby's standup routines and later as a character on Fat Albert and the Cosby Kids.
- In "The Trouble with Temple", Scotty tries to fight mind control by blurting out "My name is Fat Albert and I walk like a duck!" when asked for his name.
- Cosby and Scotty also share the hometown of Philadelphia.
- California Doubling: Unlike just about every other spy series of the time, averted (although there was still some filming done in Hollywood, there was no "Somewhere In (Insert Foreign Country Here)" cheating on this show).
- Throw It In!: Much of the banter between Cosby and Culp was ad-libbed, with the actors often tossing in references that left them Leaning on the Fourth Wall, such as Culp, in one episode, joking about how he never wins awards in a scene filmed soon after Cosby won an Emmy in a category for which Culp was also nominated. Cosby also occasionally made references to events and characters in his comedy routines.
- What Could Have Been: Producer Sheldon Leonard made concerted efforts to arrange for filming on location in both China and the Soviet Union. According to books on the making of the series, China agreed to let him film at the Great Wall and Forbidden City, but the deal fell through when the country required its film processing facilities be used, which were judged to be of too low a quality for US TV broadcast; Russia came very close to a deal until the US government objected. According to Leonard the plan for Russia was a storyline in which Scott and Robinson teamed up with Russian agents to fight a common threat (this a decade before the Bond film The Spy Who Loved Me did the same concept). After Russia fell through, a set of episodes filmed in the San Francisco region were made instead.
- Written and Directed by Cast Member: Robert Culp wrote seven episodes and also directed one of his scripts ("Court of the Lion").
The picture books:
- Milestone Celebration: I Spy Mystery, which celebrates the series' 10th anniversary, and I Spy Spectacular, which celebrates the series' 20th anniversary.
- Recycled Script: Well, not so much "script", but the Challenger books all reuse pictures from the previous books with newer (and usually much more difficult) riddles.
The video games:
- The Other Darrin: An entirely different set of children voice the riddles for Craft Projects in School Days from all the other themes. This is mostly because the original I Spy game excluded this theme, and presumably the several years long gap required the developers to find new children to voice the riddles.