Sonic the Hedgehog is known as a video game franchise with multiple adaptations and different views from the Japanese division and the western divisions. As such, some elements had the luck to being adapted into the mainline video game series.
- Sonic the Hedgehog:
- Eggman's name was localized outside of Japan as "Dr. Robotnik", which it remained through The '90s. In Sonic Adventure, Sega attempted to wean everyone onto the original Japanese name by making "Dr. Eggman" an In-Series Nickname insult but one that he was somehow fine with come Sonic Adventure 2, casually referring to himself as "Dr. Eggman" (and has ever since). However his original name also remains canon thanks to Adventure 2 as his grandfather is named Dr. Gerald Robotnik and his cousin being Maria Robotnik.
- Sonic the Hedgehog: The Movie changed Knuckles the Echidna into a treasure hunter. Half a decade later, Sonic Adventure 2 made references to Knuckles being a treasure hunter.
- Amy and Knuckles' personalities were altered to match their Sonic X interpretation after the success of the anime. For example, Amy became brattier and even more love-struck than she was in the Adventure games, while the previously serious and stoic Knuckles was changed into a quick-tempered Butt-Monkey and became more gullible. Amy's characterization went back to normal around Sonic Unleashed, but Knuckles's stuck.
- The rings around Shadow's wrists have obviously been there since Sonic Adventure 2, but the idea of them inhibiting his power was introduced in Sonic X, and has since appeared in Sonic the Hedgehog (2006).
- The concept of roboticization from Sonic the Hedgehog (SatAM) was referenced in Sonic Chronicles.
- Sonic's love of chili dogs featured in DiC's animated adaptations (Adventures of Sonic the Hedgehog, Sonic the Hedgehog (SatAM) and Sonic Underground) didn't come from any of the games, but it eventually made its way into Sonic Unleashed (though the Japanese manual to a Sonic Advance game mentioned it), which features numerous food items Sonic can obtain, including chili dogs, described as his favorite. It was also used in Sonic Chronicles and used awesomely in the intro to Sonic and the Black Knight where Sonic is summoned with two in-hand and he's given one as his birthday present from Tails in Sonic Generations.
- In the games, Dr. Eggman, while having his robotic minions, didn't have any close sidekicks; compare this to any of the animated series and comics, where his counterpart has some sort of underling (Snively in Sonic the Hedgehog (SatAM); Scratch, Grounder and Coconuts in Adventures of Sonic the Hedgehog; Grimer in Sonic the Comic; Sleet and Dingo in Sonic Underground; Bocoe, Decoe and Bokkun in Sonic X). This changed in Sonic Unleashed, which gave him SA-55 "Orbot" as a snarky direct underling, and then furthered in Sonic Colors with "Cubot", giving Orbot somebody else to play off of for humor.
- When Ray the Flying Squirrel returned in Sonic Mania Plus, he wore double-striped blue shoes and was established to be close friends with Mighty the Armadillo, traits from his Sonic the Hedgehog (Archie Comics) incarnation.
