Beta elements

From the Super Mario Wiki

Beta elements are components of a video game that, for whatever reason, are removed or altered before that game is released. Known info about beta elements usually comes from one of two sources. The first is information released about a game, by its creators, before the game is complete. The second is data found within the coding of a game that serves no purpose, but could have been implemented into the game at one point.

Beta elements get their name from the period at the end of a game's development known as Beta Testing, when the nearly complete build of the game is debugged and playtested by a small group of people. Despite this, most games are complete or nearly complete when beta testing takes place, so most beta elements are scrapped long before this period.

Beta elements should not be confused with Vaporware, entire games which never see release.

The full list of beta elements can be found here.