09-02-2018, 05:34 AM
According to programmer Jon Burton (on his Youtube channel "GameHut"), Knuckles' Bonus stages would've had their own song. However, due to memory constraints, the song had to be left out of the game, and they instead use Tails' bonus stage music. The song was eventually repurposed as "Pleasure Castle" (Twinkle Park 2) in Sonic Adventure. Jon has made a video layering the Dreamcast song on top of the original bonus stages to show what it would look like.