* BadExportForYou: The legendary pause music is not included in the Japanese version.
* CutSong: There's an unused song in the game's data, and can be found [[http://www.youtube.com/watch?v=uhnnl-eRpio&feature=related here]]. Its use is unknown.[[note]]Common theories include it being a possible final boss theme thanks to its fan name "The Armageddon", and being the music meant for the level Terra Tubes, as the level shares the same music with Surf City, which is unusual as all the other levels have their own music.[[/note]]
* OldShame: The animated series pilot is this for the creators.
* StillbornFranchise: The animated series never got past the pilot, no plans for additional animated adaptations despite the cult status of the original game. A good example of how attempts to leverage popularity in one genre to another can go awry.