and keep in mind that mountain looks to be the center piece of the land so people will be able to walk under it...there will be other "floating mountains hiding the E ticket building, i think thats where you will see more water fallsThey way they are getting them to "Float" judging by the models seems to be through the vines connecting them to the ground.
Those vines seem big enough to hide supports inside for the large structure. But you seem to be right about the smaller mountains on top. It looks like it's behind the other mountains just enough so you can't see the beam holding them together.