So I was doing a speedrun of this game, using a glitch that lets you stay in courses after getting a star, and this happened. There's a lot of weird stuff in this game. If anyone wants me to, I could probably replicate this.
Sorry to bring this dead thread back to life, but... I think this is the same as what happens when forcing the character to change whilst pausing the animation. I think it's something to do with the game not knowing which animation state Luigi is in, and therefore cycling through them all until one gets set.