Extras menu: Successfully complete Sonic, Shadow, or Silver's Story mode 100% to unlock the "Extras" option at the main menu with "Audio Room" and "Theater Room" options.
Play as Shadow The Hedgehog: Successfully complete Crisis City as Sonic.
Silver The Hedgehog: Win the Silver The Hedgehog Boss battle as Sonic.
Last Episode: Complete Sonic's Episode, Silver's Episode, and Shadow's Episode.
Free mode characters: Complete the indicated task to unlock the corresponding character in Free mode.
Amy Rose: Complete all Soleana mystery missions with an "S" rank.
Blaze the Cat: Complete all Soleana mystery missions.
E-123 Omega: Complete all GUN Commander missions with an "S" rank.
Knuckles the Echidna: Complete all Town Stage missions with an "S" rank.
Miles "Tails" Prower: Complete all Town Stage missions.
Rouge the Bat: Complete all GUN Commander missions.
Unlimited jump: There is a glitch in the purple gem you can purchase at the market. The purple gem allows you to "change size" in the description, shrinking you down to fit in small areas. However when using the gem for Sonic you are able to jump infinitely. When you press Jump while holding Activate Ge and repeatedly tap A, your character will act as if he wants to do the homing attack. However the game glitches, cancels it out, and allows you to jump as many times as desired while moving in the direction you wish to go. This allows you to get to interesting parts of Soleena or an action stage that you were not meant to access. If you die or find a alternate way to lose the gem it will be "out of stock" for some time.
Achievements: Complete the following achievements to unlock Xbox Live Gamerscore points.
Sonic Episode - Cleared (30 points): Clear Sonic Episode.