I think that if there is any part of the problem that might be called into question it would be the part about outside sources hitting and breaking the water main. Those things, quite often don't, need any help. If the water can find an escape, which I would imagine are plentiful around the Disney Property, then it would just erode away under the sod and wouldn't be hugely evident until a weight was placed above it and it would then collapse. The water might not even find it's way to the surface until something opened it up.
Seems sort of like the olden days before coffins were put in concrete containers. When the coffin rotted it would collapse due to the weight above it and all of a sudden you have this big "dent" in the ground.