corrupt data

[I wuv M4( Satar Jaèoèdoæ)]

Once me and mythos wyrm had a ssbb battle to see who was better. I beat him, and we kept a replay. Today I looked at the replay and it was normal until near the end.Then are charathers started attacking air and commuting sucide, so how changing the out come of the game so Ike (mythos wyrm) won. It shows some stuff how replays work, but the question is how was the data corrupted. To things come to mind,a small scratch on the disk that hasn't effected the game much since the day it got scratched, and me updating the wii yesterday.