In rare instances throughout the game, characters that didn't appear in Sonic Frontiers are referenced in passing, such as Cream, Shadow, Rouge, Blaze, Jet, Omega, Yacker the Wisp, and Zavok of the Deadly Six. However two of these voice lines reference Sticks the Badger and Tangle the Lemur, two characters who have not appeared in the mainline game series at all. While Sticks previously had a character page among other mainline characters on the Japanese Sonic Channel website, she has so far only appeared in the spin-off series Sonic Boom, while Tangle has so far only appeared in IDW Publishing's Sonic the Hedgehog comic book series. Thus Sonic's name drop of them in this mainline title essentially establishes the characters as canon to the Sonic game series. This Easter egg came about due to the fact that Sonic Frontiers' writer Ian Flynn is also a co-writer of the IDW comic series, and Flynn later confirmed that he added Sticks' name to the game's script both as a way to introduce her into the mainline Sonic canon, and to test the boundaries of what Sega would let him include in the game. However, he also added that he couldn't promise future appearances of her in mainline games. Flynn had originally planned for Sticks to make her canon debut in the IDW comics: the ending of the "Battle for Angel Island" arc would have revealed that she had been living on the island. This was declined by Sega. As for Tangle, while not directly related to her appearance in Frontiers, Flynn has stated that Sega fully owns the IDW characters, thus making it possible to use them in games.