Executive Meddling: The staff were pushed to create Dulcy so as the balance out the gender ratio of the Freedom Fighters. The four Antoine shorts were also a request of executives.
Fake Frenchman: Antoine, as voiced by Rob Paulsen. His character is a collection of insulting French stereotypes: mispronouncing so many words of English, misspeaking famous quotes, always scared, especially clumsy, constantly getting captured, obsessing with fine cooking and cleanliness, enving the hero and quick to surrender.
I Am Not Shazam: Some of the fans call the sorcerer "Ixis Naugus" (his name from the comics) when, technically, in the show he is simply "Naugus".
Antoine is often referred to by his comic surname (D'Coolette), while his actual name in the show (mentioned only once) is Depardieu. A bit of an odd example as the comic got "D'Coolette" from the show's bible, but the show opted to change the name after the comic had already started using it.
Another strange example is Sally. Her last name (Acorn) is never mentioned in the show proper, although most fans have adopted it from other works (her last name is provided in the show's Bible, as well as featured in the comics and as part of the video game supporting lore).
Name's the Same: Sonic is really bad for this. The show shares its official name with no fewer than five other products: the original video game, the Archie comics, the 2006 video game, a children's novella loosely based on the SatAM universe, and the franchise as a whole. Oh, and the main character of course. Most fans use the monicker "SatAM" to distinguish it as a result.
What Could Have Been: The show's third season was completely laid out and prepared, and then ABC cancelled it.
Knuckles would have appeared in the third season.
Had SatAM not been cancelled, Naugus would have taken over as Big Bad of the series.
According to the series bible, Nate Morgan from the Archie comics was originally supposed to appear in the show. Also, Snivley's original name was Quizley, and he was Robotnik's second cousin twice removed on his mother's side rather than his nephew. The bible also mentions more sinister renditions of badniks from the games such as Crabmeat and Caterkiller. While a redesigned Buzz Bomber appeared in the pilot, the others made no appearance, though like Nate Morgan made appearances in the early comics.
The bible also refers to several unused episode ideas, an early script for "Heads Or Tails" would have revolved around Princess Sally's birthday for example.
Some very early prototype designs were recently uncovered. Sally was a human at one stage, Bunnie was drawn like a Disney character and organic from the waist up (or mechanical from the head down, in another sketch), and Robotnik, as a likely result of having no visual references, was drawn as both a cyborg-pirate thing, and then a green demon overlord that looked kindof like Ganondorf if he was drawn by Don Bluth.
The show apparently would have eventually confirmed, as some fans had already speculated, that Mobius was Earth All Along, with the story set millenia after a world-purging nuclear war that wiped out humans and caused animals to become sentient. Robotnik and Snively were to be the last humans alive and had been off-planet on a space colonization mission when the war struck. After betraying and killing the rest of their crew, they returned to Earth and, due to relativity, landed after the animals had already assumed control of the planet.
What Could Have Been: This was one of many attempts at making a SatAM game revolving around stealth rather than speed. The closest these elements ever got to being included in a finished Sonic game was Sonic 3D Blast, which excised all of the SATAM elements and ended up being a Flickyrevival, and Sonic Spinball, which relegates the SATAM cast to cameos in a mini game.