Sega Illusion is an unlockable track in Sonic Riders. It can be unlocked after being awarded a gold emblem after winning the Babylon Grand Prix. Sega Illusion is an extra track and the alternate track of the Sega Carnival. This track is a combination of the Nights Into Dreams, Space Channel 5 and Chu Chu Rocket series.
The track takes place at nighttime, with many bright lights across the whole track. The track is another version of Sega Carnival, but with even more references to Sega games. The beginning area is based on Samba de Amigo, then the next area is Nights, then Space Channel 5, and finally Chu Chu Rocket. This track is a Sega-themed track, having the same music as that of Sega Carnival. In many ways, this track is more difficult than Sega Carnival, two examples being the Space Channel 5 and Chu Chu Rocket areas, which are very difficult to get through. Some of the shortcuts are illusions, so they aren't visible unless the racer is using the shortcut. Sega Illusion is the last track that can be unlocked.