You can choose between 2 Level 3 Backgrounds (It appears on Zero's Level 3 super, Rekkoha). You'll need a 
program to open Mugen characters (Fighter Factory, for example)

Just find Sprite Number 7510, and you can choose to replace with the other one i have available.

The original one is the Megaman Zero Revival picture

The extra one is an fanart by someone, but i cant remember. :(