Sonic 06 References/Easter Eggs

Despite being planned as a soft-reboot and wanting to bring Sonic back to his "roots," Sonic the Hedgehog (2006) was a complete failure among fans and new players a like. Though it may not be the horrendous monster everyone seems to call it, it was not the promised "Sonic-Next Gen." 

As a constellation prize, the 15th anniversary game still holds many hints at other games, even though it was supposed to be a "reboot." 

Notable Reoccurring Elements

• Invincibility
• 0 being a life
• Super Sonic
• Super Shadow
• Spindash
• Chaos Spear (modified)
• Flying
• Gliding
• Grinding
• Amy's Hammer

Sonic 1

• The platforms in Spring Yard Zone's boss fight are taken out by Robotnik, and the floor is also targeted in the Egg Wyvern boss fight. 
• The idea of Sonic having a having a human girlfriend originates here; in early plans Sonic had a girlfriend named Madonna. 

Sonic CD

• Time Travel is once again an important element.
• Crisis City revives the idea of a "bad future." 
• With the purple gem, Sonic can shrink and jump high. This idea is directly from Sonic CD's Metallic Madness, where Sonic is scaled down by a laser. 

Sonic 2

• The main theme "Sweet Dreams" is remixed and put at the credits in Sonic's story. 
• Aside from the game's new characters (such as Elise and Silver), Tails appears 3rd (after Sonic and Eggman), as he did in real life.  

Sonic 3

• Sonic snow boards in White Acropolis, as he originally did in Ice Cap. 

Sonic and Knuckles

• Lava Reef's fiery outside and darker inside may have inspired Flame Core. 

Sonic X-treme

• At one point Sonic's love interest--Tiara--was to be a princess, but that was later changed and the game was scrapped. This may have impacted the ideas for Sonic's new love interest, though.  

Sonic Adventure

• Both games are divided into "stories" revolving around different characters. 
• Wave Ocean closely resembles Emerald Coast. 
• The Orca reappears in Wave Ocean. 
• Once again there are chatty humans in hub worlds. 
• After meeting up with Sonic, Tails says "Long time no see, huh?" while after finding Tails in 06 Sonic says "Long time no see!"
• Iblis may have been inspired by Chaos, being an element-powered monster that transforms.
• Knuckles' treasure hunting skills are mentioned.
• Crisis City includes worn Chao in Space 3 signs; Sonic Adventure started the "Chao in Space" gag.   
• Adventure also had the first Chao Gardens, and there are signs in Crisis City mentioning a Chao garden.
• Eggman's "battleship" is another version of the Egg Carrier.  

Like in Station Square, New City was supposed to have cars. These can be found with the "Shadow New Town" glitch, but they crash into everything.  

Sonic Shuffle

• The theme of Light and Dark originated in this game. 

Sonic Adventure 2

• The "Solairs Project" was mostly likely intended as 06's "Project: Shadow."
• Flashbacks are used again. 
• Amy mistakes Silver for Sonic, just like she mistook Shadow for him. 
• GUN is present. 
• The president is mentioned.
• Rouge's treasure hunting skills are mentioned as well as used (in Kingdom Valley). 
• Rouge finds keys to move on; she hunted keys before in Egg Quarters. 
• Sonic rides a metal board in Crisis City, like in City Escape. 
• Sonic can preform a wind move with a gem. Sonic's first wind attack was from this game. 
• Eggman tricks Sonic into giving him the (fake) emerald with Amy as a hostage but traps him. He does the same with Elise except the emerald was real. 
• Canon's Core uses all playable characters except Shadow. End of the World uses all playable characters except Sonic and Blaze.

Sonic Heroes

• Eggman leaves Sonic a recording, similar to the beginning of Team Hero's story. 
• Amy turns invisible, something previously exclusive to Espio.
• Sonic "shares" his super state in both games.
• The version of the wind move for Sonic came from this game.
• Tails says "My head's spinning!" while going through loops in both games.  

Sonic Rush

• Inclusion of "new" character, Blaze the Cat.
• Blaze calling Silver naive is similar to her initial opinion on Cream.
• At the end of Blaze's story, she asks Cream, "We-We're friends, right?" Meanwhile in 06 Silver asks Blaze, "You're my friend, right?"
• The background for Princess Elise may be a nod to Blaze's fire/princess backstory. 
• One gem includes the "boost," though it does not work the same way as in Rush. 

Although there was not explanation for her presence, some unused voice clips suggest Blaze would have mentioned Sonic and talked to Amy.

Shadow the Hedgehog

• While fighting Mephiles, Shadow says, "I know who I am," directly referring to his repeated line, "this is who I am."  
• He also repeats the phrase "Who are you?! And how do you know my name...?"
• Shadow chases Eggman's train in Radical Train like with the Black Arms' tank in Lethal Highway's hero mission. 
• The Shadow/Sonic banter before Flame Core is not unlike the scene after Lethal Highway. 
• The punch/kick move preformed when without a gun is an early version of the move Shadow primarily uses in 06; he uses a version of Chaos Blast. 
• Shadow can/has to drive vehicles in some of the stages.
• Shadow drives through/destroys falling walls in both the GUN Fortress and later in Aquatic Base.
• Westopolis being a distressed city as the first level was echoed with Silver (Crisis City).    
• There is a fire tornado in Crisis City and a dusty one in Glyphic Canyon. 
• The tornado section of Crisis City for Sonic plays a lot like Cosmic Fall, including floating/moving/spinning platforms.  
• Shadow can get past a secret door after collecting 5 keys in each level. These keys resemble the ones Rouge has to find in Kingdom Valley. 
• Rouge comments on Death Ruins, expressing the desire to treasure hunt there some other time. In a similar way, she calls Tropical Jungle "Charming." 
• Shadow's theme is "All Hail Shadow." The original version was his hero-ending theme. 

Expert Mode implies that the Commander wanted to make amends with Shadow; Shadow works for GUN in 06. 

Sonic Riders

• While boarding the player must hold X before lifting off. This is how the jumps were handled in Sonic Riders (though control over tricks are not possible in 06). 

("Early") Sonic Cartoons/comics/etc

•  Sonic would often carry his love interest in a similar way to Elise (also present in Sonic CD).
• When Sara from the OVA wears her "wedding" dress, she and Elise visually look alike (pun intended). 
• Sally Acorn and Sonia the Hedgehog are both princesses, which may have inspired the title for Elise. 
• Despite the Mobian/tomboyish appearance, Sonic's (long-time) Western love interest, Sally, had reddish/brown hair and blue eyes, which may have influenced Elise to have those traits. 
• In the US, Amy was originally named Princess Sally, which again may have some influence on title. 
• Sonic introduces himself as "Sonic, Sonic the Hedgehog." He often did the same in Sonic X. 
• Shadow takes off his rings, something originating from Sonic X.
• There is a girl in the hub world who wears a shirt similar to Chris.
• The scene where Eggman sends Sonic & co to the future is similar to the 1st episode of Sonic X were he send them to another dimension (though it was not intentional in that case). 

Similarities to Sonic and the Secret Rings

The game was originally going to be a Wii version of 06 and was made at the same time.

• Sand Oasis is a level in Sonic and the Secret Rings. Two "secret" oasis-es can be found in Dusty Desert.  
• Sonic goes on an adventure with a human-like girl character, though just as a friend. 
• He tells both girls to smile. 
• Sonic is called a rat several times; Eggman calls him a rat in 06. 
• The Erazor mentions "Iblis."
• A character is killed and brought back to life. 
• The events of 06 are un-done by time travel and are forgotten or only partially remembered--as if it never happened. Since only he journeyed to the world, the events of Secret Rings are only remembered by Sonic, almost as if they never happened. 
• Both have a generally "darker" tone.