That rumour that Rare mascots Banjo and Kazooie would join the cast of Sonic & Sega All-Stars Racing? Totally true! Well, if you believe Sega.com, which is the source of the miniature, guest star–revealing box art.
TSSZ News spotted the pre-announcement reveal of the Xbox 360 version of the box art, which seems to confirm the inclusion of Banjo and Kazooie by putting the Rare pair on the cover. The Sonic & Sega All-Stars Racing with Banjo-Kazooie title is another hint that seems to confirm that at least one version will feature a bear and bird battling it out against Sonic the Hedgehog and Ryo the forklift driver on race tracks under blue skies.
While it appears that the Xbox 360 version is getting a guest appearance, none of the other platforms show cameos on their respective box arts.