Looks like Fantasmic had a little oops during the finale,
According to Firr, the pyro shot from the dragon fell out of its mouth instead of outward, so it landed on the stage and proceeded to burn. So once things cleared on stage, they cranked the fountains to soak the stage. Doesn't seem like anything was damaged nor anybody hurt, though from the sounds of it this is something that's happened before with the pyro/dragon.