- The First Inspector was originally inspired by the mysterious Inspector Goole from J. B. Priestley's 1945 play An Inspector Calls. While veteran actor Leslie French quickly established the role as his own with his portrayal of the patronising, cantankerous, but deeply moral First Inspector, he did acknowledge the debt by paraphrasing Goole's parting speech at the end of "A Timeless Man":
The Inspector: We don't live alone in the universe. We are members of one intergalactic body. We are responsible for each other. And I tell you that the time will soon come when, if humans will not learn that lesson, then they will be taught it in fire and blood and anguish. Good night.
- In the First Inspector serial "The Lost Asteroid", the use of "Bieber Variation" instead of Lagrange Point is not an allusion to Justin Bieber but to Quatermass II.
- The Fourth Inspector serial "The Robot Revolution" involves the megacorporation "Rur's Universal Robots", which is referred to by the recursive acronym RUR—an allusion to the classic science fiction play by Karel Čapek.
- The Ninth Inspector episode "The Riotous Living" of course slipped in some quotes from Charles Dickens, who tells the Inspector, "Death, fires, and burglary make all men equals." and "Your fancy London detectives come down to investigate and get absolutely nowhere because they come up with verdicts before investigating the crime more thoroughly, and they try to prove their verdicts."
- Similarly, the Ten Inspector episode "The Chaucer Puzzle" naturally includes many quotes from the poet's work, e.g. he describes his assailant as a "smiler with a knife under his cloak" and Sir John Oldcastle as, sarcastically, a "very perfect, gentle knight".
- The Tenth Inspector's proclivity for shout outs was lampshaded in the episode "Odyssey's Beginning". The Inspector, on the trail of the suspect, tells Constable Reggie, "We're going after the thin man, just like Nick and Nora Charles." Reggie admits he doesn't know them, to which the Inspector replies "Their films are before your time—that was probably a bad reference."
- In the Red Nose Day special "Spacetime", the Inspector's use of the Optic Pocketknife to make a "Bat-Climb" is a shout out to both Batman and 5 Kudretli Adamlar ("Turkish Blacula").
- The Eleventh Inspector pulled off a two-for-one shout out in "Cavemen on a UFO": "They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance."note
Shout Out / Inspector Spacetime
The writers and producers of Inspector Spacetime have always enjoyed dropping allusions to other works that have influenced the programme.