* ActingForTwo: Barrie Ingham voices both Basil and the unlucky Bartholomew. Interestingly, that makes two out of the three characters in the movie who call Ratigan a rat (the other being Olivia), and one out of two that live to tell the tale.
* ActorAllusion: When Bill the Lizard tries to assure Ratigan that he's a "big mouse" to convince him to spare Bartholomew, his voice suddenly switches to a high-pitched falsetto, referring to the particular [[MickeyMouse big mouse]] his voice actor was best known for providing.
* AwesomeDearBoy: Price on his role as Ratigan. He had stated that Ratigan was his favorite film role.
** Having two songs written for him certainly helped.
* DuelingMovies: With ''WesternAnimation/AnAmericanTail'', another animated movie about mice coming out the same year (though it didn't come out until a few months afterward). While the film made its money back, ''American Tail'' was a smash hit and, at the time, the highest-grossing animated feature ever made. Both of these things would factor into Disney deciding to re-beef their animation department.
* ExecutiveMeddling: Largely averted, as Jeffrey Katzenberg had little to no faith this movie would be any good. Most of his attention was spent on meddling with ''Disney/TheBlackCauldron'', which became a failure. Katzenberg did, however, demand the title of this film be changed from "Basil of Baker Street" to simply "The Great Mouse Detective", a move that inspired an infamous fake memo that became a category on ''Series/{{Jeopardy}}''. Two of the four directors have since said they've always hated the new title.
** However those directors may have had some solace in the title being changed to "Basil the Great Mouse Detective" in some countries, including Australia.
* IAmNotShazam: The lead dancer at the bar is listed in the credits as "Miss Kitty Mouse," but, Fanon aside, this doesn't actually appear to be her name. Rather, it's a description of her. She isn't "Miss Kitty Mouse," but "the Miss Kitty mouse."
* WhatCouldHaveBeen: Music/{{Madonna}} was considered to voice Miss Kitty and perform the song "Let Me Be Good To You".
** This isn't as far-fetched as it may seem when one listens to Madonna's jazzy showtunes on the ''Film/DickTracy'' soundtrack.
** Olivia was originally planned to be older, acting as a potential love interest for Basil, but it was later decided she should be a child to make her more sympathetic.
** Creator/JohnCleese was the first choice to voice Basil.
** Ratigan's original design was [[LeanAndMean very thin and frail-looking]]. They changed it after Creator/VincentPrice was cast [[InkSuitActor to reflect Price's larger build]]. Glen Keane also says that he based it partially on then-head of the studio, Ron Miller, an ex-football player.
** Originally, Ratigan was a very ugly mouse ''mistaken'' for a rat, instead of a rat ''willingly'' passing for an ugly mouse.
----