Franchise: Sonic The Hedgehog

In a post titled "SONIC THE HEDGEHOG: One Year Later...", Karl Bollers (a former writer for Archie's Sonic the Hedgehog comics) revealed numerous plans that he had intended to include in the comics following Issue #134 that were never used, such as:

• Sonic and Amy becoming a couple after being stranded at sea together, keeping it a secret from Sally.
• Tails reuniting with his parents by traveling into space on a modified Tornado.
• Amy's origins being explored in a fuller adaptation of Sonic CD.
• Knuckles departing Angel Island after learning that his presence exposes the location of the Master Emerald, going on a global pilgrimage to learn martial arts and battling a Dr. Eggman controlled-Monkey Khan while himself under the control of the Iron Queen before discovering the Master Geode.
• Sally being a pawn in a villainous plot by the corrupted Source of All and Ixis Naugus to prevent the future first previewed in "Sonic In Your Face!".
• Bunnie and Antoine breaking up due to a change in Antoine's personality, with Bunnie's origins later being explored and her true name being revealed as "Scarlette O'Hare" (which may have served as the inspiration for Scarlette Rabbot from Sonic Universe's "Fractured Mirror" story arc, and Bunnie's codename when she was in the Metropolis Egg Army in Issue #255).
• Antoine gaining his scar due to an accident with a knife and becoming a villain after allowing himself to be possessed by a corrupted Source of All in hopes of winning Bunnie back.
• Rotor retiring from field duty in order to pursue a role analogous to that played by "Q" from the James Bond franchise.
• The Source of All surviving Robotropolis' destruction and reconstituting itself in a remote mountain range, where it began to exert control over King Max, brainwashing the Arachne Clan and another group of Spiders known as the Strand, and possessing Antoine while under the control of Ixis Naugus.
• Locke and Lara-Le putting aside their previous disputes to help raise Kneecaps after his father Wynmacher ends up in the Egg Grape Chamber.
• Dr. Robotnik kidnapping Hope Kintobor under the pretense that he is the only correct choice to be her legal guardian, while using her as bait to lure in Shadow.
• Ixis Naugus attempting to return by transforming Max's body into a duplicate of his own, only to be thwarted by the destruction of the Crown of Acorns.
• Mammoth Mogul beginning to age rapidly due to his original Chaos Emerald running out of energy, forcing him to seek out alternative sources through illicit archaeological expeditions and hiring mercenaries like Nack the Weasel. The Master Geode, a powerful gemstone that would fulfill Mogul's needs, would be contested by him, the Iron Queen, Robotnik, and Rouge the Bat.
• Nate Morgan surviving the destruction of Robotropolis and being de-Roboticized by the Bem, returning as Coconuts' amnesia-addled ally, who creates a new Metal Sonic, Metal Amy, Metal Knuckles, and Tails Doll that are mistaken for Robian versions of the heroes.
• Snively taking up a fifteen foot-tall mechanical battle suit and the alias "Skarkus" in pursuit of revenge against Robotnik for leaving him alone against the Xorda, leading to an alliance between him and Shadow.
• A.D.A.M. and Nicole becoming romantically involved, leading to A.D.A.M. seizing control of the Shadowbot army and leading them from New Megaopolis to Knothole.
• A new Dingo Regime leader named Colonel Mange being introduced, with Croctobot, Jack Rabbit, and Gala-Na being reintroduced as Robotnik Sub-Bosses over Downunda, the Great Desert, and Albion. This would have led to the disappearance of the Downunda Freedom Fighters and a confrontation involving the Mercian Freedom Fighters.
• Evil Sonic coming to enjoy impersonating Sonic and enjoying the love of his parents and adulation of his people, leading him to plan to eliminate Sonic and permanently take his place.

Additionally, in the aftermath of Ken Penders' lawsuit against Archie Comics, Bollers has confirmed that he now owns the rights to all the characters he created for the comics, such as Mina Mongoose, Ash Mongoose, and Hope Kintobor.

On June 23, 2016, Sega released a YouTube video titled "25 Years of Sonic the Hedgehog!", a video going through an abridged timeline of the Sonic franchise's games on the anniversary of the first game's North American release. Strangely and controversially for a celebratory video, the video makes multiple snide remarks towards the games featured, some that are innocent in nature (such as Sonic the Hedgehog 3's description mentioning the "Knuckle Chuckle" meme and Sonic Heroes' description referencing the infamous "Look at all those Eggman's Robots!" translation error) while others very directly mock flaws and criticised elements of the games, such as Sonic 3's referencing the "barrel of doom", Sonic 3D Blast's description poking fun at how the Flicky AI would run away from Sonic, 2006's Sonic the Hedgehog not even receiving a description and simply showing its loading graphic, and Sonic Colors' description stating that it is where "Sonic in 3D finally finds its footing", a statement that is technically true when looking at critical reception, but tends to aggravate fans of 2000s-era Sonic games.

In August 2016, Scott Fulop, a former editor and writer for Archie Comics' Sonic the Hedgehog comics (whose notable contributions include the characters Mammoth Mogul and the Fearsome Foursome), began pursuing legal action against Archie Comics and Sega of America for the unauthorized use of his characters and reprinted stories. In the lawsuit, Fulop claimed he was owed six figures in royalties for his creations (having made 15 characters for the comic), and gave nearly a thousand examples of Archie either wrongly using his characters or reprinting stories involving them, and how he (through his company Narrative Ark) sought damages for copyright infringement from both Archie and Sega due to them apparently failing to compensate him for his works. He also alleged that Archie engaged in "deceptive business practices, unfair competition and unjust enrichment." As part of this, he attempted to invalidate copyrights on his characters filed by Archie in 2011 in response to fellow former writer Ken Penders' own copyright filings, who had also infamously sued Archie for similar reasons. However, in September 2017, the judge ruled in favor of Archie Comics due to various flaws in Fulop's claims.

"TailsTube" is a webseries that began airing on March 22, 2022. Described as a "fun and informative, Tails-hosted show about all things Sonic", the series is hosted by a VTuber version of Miles "Tails" Prower, as he answers questions from fans about the Sonic the Hedgehog franchise, often featuring special guests from throughout the series. The series is notable for explaining various aspects of the series' lore. For example, the first episode debunks a popular fan theory that claims that Sonic's world and Earth are two separate planets, and the fourth episode confirmed the existence of a multiverse in the series, as well as establishing that "Classic Sonic" and "Modern Sonic" are not separate entities from alternate dimensions, instead being the same character's past and future variants. The sixth episode also sees Tails mention Jewel the Beetle and the Restoration, two prominent parts of IDW's Sonic the Hedgehog comic book series, further connecting it to the game series canon.

On April 8th, 2022 (the American release date for the film "Sonic the Hedgehog 2"), former Archie Comics writer Ken Penders revealed that he was contacting his legal team in regards to the Echidnas and their backstory featured in the film. According to Penders, both Knuckles' unnamed father and the workings of the film's depiction of the Master Emerald were derivitive of two of his characters, Locke and Enerjak. Despite the fact that the powers of the game version of the Master Emerald had been established back in 1994 with the release of Sonic & Knuckles, Penders has claimed to have legal ownership over the ideas he created in 1996. However, as of March 2024, no lawsuit has materialized.

According to Bug! executive producer David Warhol, developer Realtime Associates was at one point contracted by Sega of America to create a Sonic the Hedgehog game as a launch title for the Sega Saturn. However, shortly after Realtime Associates agreed on a contract, Sega of Japan denied them permission to use the IP. Realtime Associates instead continued with the project as a new IP, Bug!, based on a cancelled project for the Sega Genesis.

Since Sonic was very popular in English speaking countries, one of Sonic's quirks in Japan (performed by Junichi Kanemaru) is that he may speak English at times, unlike other characters.

In 1993, Sonic the Hedgehog became the first video game character to appear as a balloon in the Macy's Thanksgiving Day Parade. The balloon popped on it's one and only flight by being pushed into a lamp post by strong gusts of wind, hurting a kid and a police officer on it's descent. Because of this incident, the balloon was retired.

A second Sonic balloon based on his modern redesign was used between 2011 and 2013 to celebrate the series' 20th anniversary, and was brought back one more time in 2021 in accordance with the series' 30th anniversary.

In the 1990 arcade racing game Rad Mobile, there is an air freshener of Sonic that is hanging from the rear-view mirror. This marks the first time Sonic has ever made an appearance in a video game, which, interestingly enough, predates the release of Sonic the Hedgehog in 1991.

The trademark Sonic Emblem, as featured in Sonic the Hedgehog and subsequent installments on the Sega Genesis, is based off of the logo from the 1988 Sega arcade title, Wonder Boy III: Monster Lair.

There is a series of posters in several Sonic games advertising a movie series called "Chao in Space". These posters also feature the names of various Sonic characters.

In 2010, SEGA de-listed every single Sonic game with anything less than an average Metacritic score so that they could not be bought new at retail or downloaded from console-based online services. This was in order to increase the value of the franchise to prepare for a "comeback". Ironically, Sonic Free Riders, released the very same year, has a below-average Metacritic score of 47 out of 100.

Jon St. John, the voice of Duke in the Duke Nukem games, also voiced Big the Cat for several Sonic games starting with Sonic Adventure up until Sonic Heroes.

In all of the Sonic Riders games, there is a gear titled "The Crazy", which resembles a taxi. This is most likely a reference to another SEGA series, Crazy Taxi.

Sonic's shoes were inspired by Michael Jackson's boots and the color scheme of Santa Claus. Sonic's personality was inspired by Bill Clinton.

The English script for Sonic Colors, as well as other 3D Sonic localizations up to Sonic Forces, was partially written by Ken Pontac, known for working on children's programming such as LazyTown, Arthur, and Bump in the Night (the latter of which he co-created), and Warran Gaff, best known for his and Pontac's work together on the adult cartoon Happy Tree Friends. Pontac and Graff's renditions of Sonic were significantly more lighthearted than earlier or later 3D games, a highly requested shift at the time that would prove controversial after a few games. This disdain for Pontac and Graff's writing style led Pontac to decline from doing Sonic panels at conventions out of fears that vitriolic Sonic fans will visit and harass him.

Dr. Robotnik was created to be the opposite of Sonic, and to be the bad guy. During the development of the game, there was a growing debate between developers and environmentalists, and Robotnik was created to represent machinery and development, as apposed to Sonic, who represented the environment.

His egg shaped redesign came from Naoto Ōshima wanting to give the characters designs that were easy enough for kids to draw.

The skid noise made when Sonic stops running comes from Out Run, an earlier SEGA game.

Tomoya Ohtani, a recurring composer for the series, frequently samples a portion of the famous drum break from the song Amen, Brother by The Winstons. This portion can be heard in 'Vs. Orcan' and 'Skullian' from Sonic Colors, the extra boss theme 'Boss - Big Swell' from Sonic Rush Adventure, and 'Cool Edge Day' from Sonic Unleashed, just to name a few.

Sticks the Badger from the Sonic Boom sub-series resembles Aika from Skies of Arcadia, another Sega game. Both Sticks and Aika use a boomerang as their weapon of choice, have nearly identical hairstyles and have orange as one of the predominant colors in their design.