- Christmas Rushed: The 3DS version, which was rushed out in about six months or so, compared to the console versions which were in concept since at least 2008. While the final product certainly wasn't a disaster by any stretch, it lacks content compared to the console versions and it's obvious that some corners were cut (including the rival races, which take place on improbable stages).
- Fan Nickname: The fire tornado in Classic Crisis City that drags the goal post away has been affectionately dubbed the Trollnado. The goalpost is called the Trollpost.
- Flip-Flop of God: A financial report confirmed that it would go to the Nintendo 3DS and PC... then it was disconfirmed in an update to said paper. Only for the 3DS version to be reconfirmed later.
- And then the PC version was reconfirmed much later.
- God Never Said That: Takashi Iizuka in the Sonic Boom 2013 - Q&A said Sonic Generations is an anniversary game, which causes certain fans to interpret as "non-canon", despite that this would also apply to every other anniversary game, such as Sonic Adventure 2. note
- Meaningful Release Date: The first demo was made available on June 23, 2011, exactly 20 years after the first Sonic the Hedgehog was released. This is fitting, as it's a game about Sonic's history.
- The second demo was released on October 19, 2011. When Sonic Generations was one of the Daily Deals for the Steam 2012 Summer Sale, it was discounted to $10.19.
- Milestone Celebration: Developed as part of the franchise's 20th anniversary.
- Name's the Same: The Time Eater is a monster and the main villian of another Sega-related game that has a time travelling plot and has two playable protagonists and one of them is a blue-themed character that sports a red shoe and is related to gold rings. Monster in said game looks like the unholy fusion of Perfect Chaos and the Biolizard, with a bit of Biollante.
- No Export for You: The massive collector's edition set is exclusive to Europe and Australia.
- And it was later revealed that Japan was getting an exclusive special 20th Anniversary set as well. 'Tis a sad year to be an American Sonic Fan...
- The Other Darrin: The entire English voice cast was replaced, the sole exception being Mike Pollock, who stayed in the role of Dr. Eggman (and, as of 2018, is still voicing him).
- Role Reprise: In the French dub, all of the voice actors from Sonic X reprised their respective roles, with the exception of Vector. They've since continued to voice these characters in the subsequent games.
- Talking to Himself: Quite literally with Classic and Modern Tails, who are both voiced by Kate Higgins. Averted in the Japanese version, where Classic Tails is voiced by Takuto Yoshinaga, while Ryo Hirohashi voices Modern Tails.
- And both Eggmen.
- Urban Legend of Zelda: For a brief while, it was rumored that Classic Sonic is mute largely because they couldn't get Jaleel White to return to do his voice. It turns out that White was never approached by SEGA to voice Classic Sonic.
- There was also a rumour of DLC stages being released. Apart from the Casino Night pinball minigame this was false (Though Sega did mention that they did consider making a DLC stage based on Wacky Workbench)
- What Could Have Been: According to Word of God, they had hoped to make all acts playable by Classic and Modern Sonic alike. Indeed, it is possible to hack or glitch the game so that you can play Modern Sonic in Classic levels, viewed from a 3D perspective — the Classic levels look very unfinished when viewed in this way, however. The game reportedly crashes in various ways when attempting these hacks: e.g. when Classic Sonic triggers a rainbow loop, or when Modern Sonic doesn't stop after the Classic Finish Panel and falls through the level geometry... You can, at least, unlock the Modern Sonic homing attack, à-la-Sonic 4, for Classic Sonic, after collecting enough red rings in the Modern Era Act 1 levels...
- Big's voice actor Kyle Hebert recorded lines of dialogue for Big's part of the game, but Big was later scrapped from the game's plot and levels. It's currently unknown where in the game he would've been, but Hebert's name remains in the credits, and Big's statue can be seen in the Statue Room.
- Sega mentioned that they planned to make a stage based on Wacky Workbench, initially dropped to keep the "3 stages per era" set-up and later dropped fully when they decided against full DLC stages.
- Some digging through the very first demo of the game (time-limited) reveals an option to change the HUD's appearance. This can now only be achieved through mods.
- Originally the game was going to have three Sonics, with the third being "Dreamcast Sonic", who would have been voiced by Ryan Drummond. However, Ryan turned down the offer, so Dreamcast Sonic was scrapped and the final game had just Classic and Modern Sonic. Also, one of the staff at Sega of America did say that if Classic Sonic were to speak, he would have to be voiced by Jaleel White, but Jaleel was never approached about doing the role and they eventually decided to make Classic Sonic mute.
- Cash Cash did the remix for the American Stardust Speedway theme for Generations, as noted in the liner notes for the remastered Sonic CD soundtrack, but decided against having in the game since Generations already had the "B" Mix remix they made and felt that the soundtrack should have something extra. This is also why the song loops on the soundtrack.
- Word of God: Confirmed Sonic Heroes was in the Dreamcast era.
- Word of Saint Paul: Ian Flynn, head writer of Archie Comics' Sonic the Hedgehog, believes the Time Eater is what remains of Mephiles after the time reset from Sonic 2006. This is not confirmed nor denied by Sega.
Trivia / Sonic Generations