- Author's Saving Throw:
- Seems the writers of Return to Zombie Island realized the wasted potential in not fully using Elvira, so this movie seeks to rectify that.
- For those taking issue with Velma's behavior in the previous two movies, she gets called out here and also comes to realize how close-minded and stubborn she became.
- The film isn't a continuation of a prior story or incarnation like Curse of the 13th Ghost and Return to Zombie Island, likely due to how controversial both films were with handling elements of the prior material. The film is also looser regarding franchise continuity, mixing and matching elements rather than trying to awkwardly Retcon older stories. The film does, however, resolve a plot thread from both of those films, that being the Sheriff turning out to be Evil All Along. According to Maxwell Atoms in the What Could Have Been entry, this decision was made before he came on board.
- Cargo Ship: Once again, Fred and the Mystery Machine. He even refers to it as "my love".
- Fridge Brilliance: Another reason the gang failed to recognize the Sheriff as past enemy Cutler Toe — aside from lack of a beard, hat covering the baldness, and altering voice and demeanor — the picture of the unmasking from his monster disguise shows that the gang found Toe's oufit so disgusting that none of them could stand to even look at him directly.
- Inferred Holocaust: The town of Crystal Cove (or at least the town square judging by later dialogue) is presumably destroyed by collapsing into a cataclysm, possibly killing god knows how many people assuming they didn't evacuate in time.
- Just Here for Godzilla: Even if you don't regularly watch the Scooby-Doo movies, you may decide to give this movie a go if you're a Batman fan to see the appearance of The Scarecrow. Or you're a fan of Bill Nye and/or Elvira, either of them could be strong selling points for the movie as well.
- Les Yay: Daphne is really into Elvira.
- They Wasted a Perfectly Good Character: Even ignoring those who don't have that much of a problem with Scarecrow being the main villain (see below) for a second, many fans were still disappointed to find out that despite being heavily advertised as such that his total screen time only amounts to five minutes, with his only major moments being at the beginning and then towards the end of the second act, feeling like a bit of a waste especially since Dwight Schultz is clearly giving it his all as well as the interesting Worthy Opponent dynamic he has with Velma. The most common speculation being (like most behind-the-scenes aspects of the film) Executive Meddling, specifically from the DC Comics side of things.
- They Wasted a Perfectly Good Plot:
- The premise of Scarecrow leading an army of monster pumpkins to wreak havoc is an entertaining idea, but Scarecrow is a Red Herring. The movie being your standard lighter-toned Scooby fare means that we dont get what couldve been a genuinely creepy, scary film.
- The revelation about an earlier script has lead to some criticism about the film's lack of covering some elements from the previous two movies. The Mystery Machine's random comeback only to be taken out early seemed weird. The promotion of Bill Nye and Scarecrow into important roles also doesn't suit well given that the movie may have instead have given other Scooby characters a chance to return. The reveal of The Sheriff as the bad guy but to be someone we had never heard of before also seems like a very weak choice given hundreds of Mythology Gag options there could have been.
- Trailers Always Lie: The trailer makes it seem like Jonathan Crane, aka the Scarecrow, is the Big Bad. Instead, he's being framed by another party, who's been plotting against Mystery Inc. since Scooby-Doo! and the Curse of the 13th Ghost.
- Unexpected Character:
- Jonathan Crane aka The Scarecrow is featured in what at first is an antagonist role but turns into a support role.
- Elvira is also pretty surprising due to not being traditionally associated with family entertainment (well, outside of Knotts' Berry Farm anyway) and being pretty obscure to most people born after The '80s. However, this marked her second inclusion in this Scooby series.
- To a lesser extent, Bill Nye also put in an appearance on Scooby-Doo and Guess Who?, but him also appearing in a Direct to Video movie was surprising.
- The return of the Sheriff is a near aversion, only because after he returned in the previous movie some were expecting he wasn't done.
- Due to Red Herring not having appeared in any Scooby Doo media since A Pup Named Scooby-Doo, seeing him briefly return in a cameo appearance with his own Halloween-themed business can come as a surprise.
- We're Still Relevant, Dammit!: The movie really gluts itself on late 2010s/2020 slang, catchphrases, and elements. When Velma is explaining the mystery at the beginning, Daphne keeps spouting phrases like basic and womp womp; air drop and mic drop are used during Bill Nyes introduction; and Scarecrow even calls the gang the avocado toast generation.
YMMV / Happy Halloween, Scooby-Doo!