Musicless overworld

From Glitches

From the game Super Mario World for the Super Nintendo

Beat the Sunken Ghost Ship a second time. Once you beat it, there will be no music in the overworld. When you walk from place to place, you'll still make noises, and if you enter an area with different music, like the Forest of Illusion or a pipe, then the music will be restored. This probably happens because the ship-collapsing animation was supposed to happen, but it couldn't; the programmers did not expect you to do that level multiple times.