Spongebob and friends meet the great mouse dectecive is where Spongebob and friends meet Basal of baker street, and face his arch-rival, Ratigan, and the villain leage.
Of note is the addition of the plot of Atlantis Milo's return, and two new characters, Abbot and Costello as evil rats working with Ratigan.
- Unlike the real film, Ratigan's last words are, "There's no escape this time, Basal!"
- Also unlike the real film, Toothless the Night Fury angrily roars at Ratigan, and the sound makes Ratigan fall off of the tower, rather than the sound of the bell of Big Ben making him fall off.
- Also unlike the real film, Fidget, along with Abbot and Costello, was captured by Toothless.
- Since Fidget was captured, the movie was incredibly altered, like the showdown with Ratigan taking place at a mysterious mountain where the villlain league was hiding and preparing to invade the Buckingham palace, and after such battle, Hiccup and Toothless were pursued by Ratigan and the red Red Death, who like the other one, was defeated the same way the first one was defeated, and crashed into Big Ben, much to the amazement of Icky that it still stands regardless that the Red Death crashed into it.
- Originally, Ratigan was gonna die from the explosion from the Red Death after it crashed, and the fight scene inside Bg Ben was going to be deleted, but was requested to stay by popular demand, so Ratigan somehow avoided the powerful explosion along with Basal.
- In the real film, Ratigan had a pet cat named Felicia, but she was removed as a character due to anti-catism, though negative over-wightness, and the way she was defeated, chased by Toby, and then she stupidly jumped into the royal dog pen, and was replaced by Savio, as Ratigan's pet snake. Ratigan's other pet was the Red Death, which appeared later at the climax.
- Scar was also in this but unlike the other villains, he run off mid-climax, much to the anger of Zira and the other leaguers, to avoid Simba discovering him till Spongebob and Friends find the black cauldron. This was requested by Lionkingrulez because he didn't wanted Scar discovered by Simba yet, but then, he was cool with Simba and Friends discovering Scar in Spongebob and Friends find the black cauldron cause he said it would helped his series a little.
- Fidget reforms and joins the shell louge squad. Supervideomaniac personally thinks this is a better ending for Fidget then what really happened to him in the real film and other crossovers, of him being thown off by ratigan to the river below.
- Doodle, a character who took part in the moisode, was intended to appear as one of the major characters, even then be found by the villain league to join them as what they thought he was the bearer of the Atlantean Spear, but Tman requested to have Doodle defeated too soon by the Vultures.
- Savio sings Hexxus' song "Toxic Love" from Ferngully, but it doesn't make any sense that while he sings, he says he loves toxics and was locked in a tree, and he wants to destroy the enviornment because of 3 things: 1.He's a boa constrictor, so he not venomous, 2. He was never locked in a tree, and 3. He would never want to destroy the enviornment because he basically lives in it.
- Like in Winnie the Pooh in The Adventures of The Great Mouse Detective (in which Winnie the Pooh was kidnapped along with Olivia by Fidget) and Littlefoot and The Adventures of The Great Mouse Detective (in which Littlefoot, Ducky, Petrie, Chomper, Guido, Ash, Pikachu, Misty, Togepi, Kyle, Cartman, Mickey, Pluto, The Vultures, Jiminy Cricket, Zazu, King Julien, Maurice, Mort, Jesse, Randolph, Jean-Bob, Speed, Puffin, Mikey, Mouth, Data, Chunk, Sebastian, King Louie, Kenai, Koda, Rutt, Tuke, Roger, Chanticleer, Jack, Scooby-Doo, Shaggy, Elsa, Dweeb, Charlie and Itchy were kidnapped along with Olivia by Fidget), SpongeBob and Sora will be kidnapped with Olivia by Fidget. Unlike those Projects, however, Fidget was actselly stopped, and made a change of heart due to knowing Kairi and having discovered Batty Koda being his long lost couzin.