I don't know if anyone knows about this(it might only be my copy), but at the end of the level, Chocolate Island 3, when you supposed to go up the bean stalk to get to the end point, instead of doing it normally, if you get a Yoshie and run, then jump off Yoshie in front of the end point and cross it, the world map will be discoulored untill you go into another level. I thought it was neat.
I'm figuring you're talking about Super Mario World, right?
o yea sorry.
Thats an interesting sounding glitch. I'm not sure I could do that though, my map is already permanently discolored (from collecting everything).