Aurelion Sol Bug

During a custom game, my brother, playing flew over the wall near the red's first mid turret. The game glitched and corrupted the textures. The map texture was the worst of this bug. It became white with random lines of color throughout. Upon Alt+Tabbing the textures for the map was fixed. The only thing still corrupted was his basic attack animation. He then left the game and found out he had left his masteries page open. I'm not sure what cause this bug in the first place. Upon reconnecting everything was fine.