* {{Fanon}}: Many people have interpreted the eponymous character as an alien, in no small part due to his hyponotic abilities and the fact that his eyes are green (as in, ''fully'' green, not just the irises).
* SugarWiki/MomentOfAwesome: The original Demon Headmaster appears in the final episode of season one of the 2019 series, revealing himself to be the real BigBad of the series.
* NightmareFuel: Some of the [[https://images-na.ssl-images-amazon.com/images/I/41o0Bqnf2zL._SX285_BO1,204,203,200_.jpg front]] [[https://images-na.ssl-images-amazon.com/images/I/51McfajTjXL._SX313_BO1,204,203,200_.jpg covers]] [[https://images-na.ssl-images-amazon.com/images/I/41VCH12BQ3L._SX302_BO1,204,203,200_.jpg of certain]] [[https://southernbendbooks.files.wordpress.com/2014/06/demon-headmaster.jpg editions]] of the books are pretty disturbing to look at. [[TheFourthWallWillNotProtectYou It's easy to believe that the Headmaster is actually staring at you, the reader.]]
* ParanoiaFuel A good example for a 100+ page kids book actually, is the Headmaster's power. Unless you're one of the very select few who can resist him, you end up doing everything he says even if you don't want to and you won't know why. All you would know was that you saw a innocuous, kinda funny looking fellow who you may remember falling asleep near. We see it first hand from Dinah's perspective in the books.
** What's worse is that he's able to use technology to the same end, meaning you don't ''have'' to see him.
* ShipTease: Downplayed with Dinah and Simon in the fourth book - they are never shown to be more than friends, but their mutual interest in science and nature quickly leads to them working together. Had the Hunters not moved back to their old area, it is possible something stronger could have developed between them.
* TearJerker:
** Dinah's brief HeroicBSOD after snapping at Mrs. Hunter in Episode 4.
** Dinah, Harvey and Mrs. Hunter finding Lloyd comatose after he was stung by the [[WickedWasps The Giant Wasp]]. Mrs. Hunter's reaction can really hit home for any parent who's suffered a similar experience.
** Dinah feeling increasingly isolated from SPLAT, when Rose drives them to believe she is more interested in science than in Lloyd's condition. At one stage, she is even crying silently on her bed!
* TheyChangedItNowItSucks: Some fans of the original books were a little disheartened to learn that the new [=2010s=] books would feature a new group of schoolchildren instead of SPLAT.
* UnintentionalPeriodPiece:
** Season 1 makes it clear that it is set in TheNineties. One episode features Dinah using a tape recorder to attempt to record the Headmaster, whereas were the episode to take place in the 2010s, she would probably use a smartphone. Another episode features a computer room with large bulky monitors.
** Season 3 suffers from this the most. A number of episodes feature the characters going to a cyber cafe to use the Internet, with computers with large monitors, and communicating through Internet chat room. Cyber cafes have become mostly obsolete as most people now have a home internet connection or access the internet on their phones through public wi-fi, computer monitors are now flat screen, and people communicate through social media and instant message apps rather than chatrooms. One episode also features a cameo by then-current Prime Minister UsefulNotes/TonyBlair.
* WinBackTheCrowd: The decision to have [[spoiler: Dinah]] appear in the new series for those that complained about the new books not featuring SPLAT.
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