These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Inspector Spacetime
Alas, Poor Scrappy: Jeffrey was generally loathed throughout fandom until his heroic sacrifice.
Angst? What Angst?: While the actual transformation was more difficult than usual, the Fifth Inspector got used to being a woman very quickly.
Broken Base: The "Blogon" vs. "Blorgon" war has bitterly divided the fanbase ever since the alien race appeared in the series' second episode. For the record, Brian Swansea, the Welsh in-house designer who helped create the iconic Inspector Spacetime enemy, used to insist on trilling the R in "Blorgon", while the posher Leslie French preferred to drop it.
The Infinity Knight High Command's Black Museum comes from the nickname of Scotland Yard's Crime Museum.
The Rostraans are named them after the Roman Rostra, the orators' platform that was also used for displaying the heads of defeated enemies of state during the late Republic.
The Inspector refers to the Maharini's 10-dimensional henchbeings as "p-braned" in "Space or the Maharani".
The chrono-crossbows in "The Envoys of Entropy" shoot"arrows of time".
The temporal disintegration of the planet Kadakeys alludes to two of Salvador Dali's Surrealist paintings in "The Persistence of Memory".
Cardinal Continuum from the serial "The Last Minutes" gets his name from mathematician Georg Cantor's set theory work on "the cardinality of the continuum" (and the Lemniscate he uses is named after another term for the infinity symbol "∞").
Ham and Cheese: The Sergeant was played in the Made-for-TV Movie with infectious enthusiasm, making something genuinely funny out of a movie trying much too hard for comedy and very nearly salvaging the whole mess.
Harsher in Hindsight: Although the programme's typical ideas of what the future became obsolete soon enough, a few stories turned out to be coincidentally prescient.
The serial "The Revolution" climaxed in street battles between the Circuit-Chaps and the Paris police—which would soon look all too similar to the May 1968 protest's.
In "Exodus of the Blorgons", the Inspector successfully detects the space-time rifts his nemeses are using to relocate to London by installing special surveillance cameras across the city. Forty years later, the UK has an estimated 1.85 million CCTV cameras.
Hilarious in Hindsight: You remember that guy who criticized the Inspector's time machine's look in "The Waters of Venice". He's the Twelfth Inspector now.
The Optic Pocketknife has a thousand settings, but you'll only need the edge.
The intro to "Mark of the Maharani" has been making the rounds on YouTube in recent years and has spawned a few Image Macros. It consists of the Sixth Inspector (Graham Chapman) sitting in a darkened room, legs crossed, pipe in hand, staring unblinkingly at the camera, and reciting a summary of the upcoming episode in reversed Latin. While disquieting, the rumor that he addresses the viewer by name is, of course, completely apocryphal and easily disproven, as is the rumor that his eyes vanish at any point during the intro and are replaced with smooth, blank skin. Rumors that the shadows behind him contain roiling black shapes, like tentacles or smoke, were probably inspired by visual artifacts from the VHS transfer. These rumors are silly and should not be investigated further.
"It's not (where, what, who or how) but when."
"Look out, Blorgons!"
Narm Charm: Naturally. It's part of the appeal, especially in Classic Spacetime. Those early Blogons! Adorable.
Nightmare Retardant: The titular monsters in "The Kittens". (They're just so darn adorable when they're pretending to eat people!)
A great many science fiction and fantasy characters and concepts actually originated in IS:
Despite what the books' fans say, Nymeria of Kraken V was created long before George R R Martin even imagined the name Westeros, much less its history and legends.
Fans of that other show would do well to note that Inspector Spacetime began airing an entire year before it. In fact, the former show takes a lot of cues from IS.
Paranoia Fuel: The Snarling Lions will attack you as soon as you look at them directly. Made even worse in one of their later appearances, where it's revealed that even looking directly at the reflection of one will cause it to be aware of you. Imagine the Inspector's unease at having to hunt one down in an Amusement Park of Doom's Hall of Mirrors.
Poor Man's Substitute: In the trippy Second Inspector serial "The Time Bootleggers", Hamish Wilson's character Aiden is temporarily replaced by some bit actor from Emergency – Ward 10 named Frazer Hines.
Rescued from the Scrappy Heap: Stephen Fry's turn as the Inspector was not well received in many quarters. He started on the road to redemption with his brief appearance in the Eighth Inspector TV-movie, particularly during his scene with the now-elderly Dynamo. And then, years later, when the show was revived again, he appeared in the episode "Fry and Laurie", playing not his version of the Inspector, but an epically hilarious send-up of himself.
Retroactive Recognition: Sometimes it seems like every single famous British actor in the world started out playing a villain or Red Shirt on Inspector Spacetime. Perhaps the earliest example was Michael Caine, who hit it big in Zulu just months after appearing as the terrifying Cockney Radarman leader in "The Radarmen".
Seasonal Rot: The Seventh Inspector's run is generally regarded as the series' lowest point, mostly due to the banal, repetitive and/or appalling scripts (though as noted above Stephen Fry's Inspector has his detractors as well.) "Cattlefield", with its ghastly abundance of Toilet Humor, may be the worst of the worst.
Shocking Swerve: The First Inspector's abrupt death/regeneration near the end of "The Lost Asteroid" could be seen as an example of this.
Shoo Out the Clowns: "Coco" Coates is arguably an example; the arrival of the rather dour Second Inspector saw her replaced as the Inspector's Associate by the sword-wielding Aiden.
The show's notoriously low budget often caused this. The most infamous example was the episode where the "monster" was clearly a carton of eggs with Dracula fangs glued on.
"The Ocean's Teeth". Just, "The Ocean's Teeth". Elephant-shark hybrid monsters are not supposed to have mouths with visible hinges (that appeared to have been taken off a rusty old door)! Sometime you could even see the costume operator's fabulous red hair in the Makara's mouth, making viewers certain that there would be a big Scooby Doo Reveal and cursing of meddling kids by the end. How the actors managed to keep straight faces is a miracle for the ages.
The "ejector seat" scene in Retirement Home of the Circuit-Chaps is another infamous example, complete with a "boinging spring" sound-effect.
Visual Effects of Awesome: Despite the above, occasionally the show pulled it off. "The Return of the Infinite Cyclorama" is often cited as the original series' highpoint in this area, especially the now-iconic shot where the Cyclorama re-emerges and devours the Blorgon Battlehub.
The Woobie: Almost any Associate, but Capt. James Haggard deserves a special mention.
Also Thorough Visor. To quote one critic: "It is an eternal testament to Hugh Laurie's ability to produce puppy-dog eyes that the man is able to make you feel sorry for him even as he jaunts around the universe half-naked crammed into a phonebox with three attractive women."