Visualization as in pre-vis ... concepts and vis? Not a sound thing ... that would be post production or audio post, and don't forget the transfer, they most likely used Company 3 in Santa Monica and those guys aren't cheap.
As for concept phase taking a few hours, thats spoken like a true producer/account exec. People think its easy.
I produce now, but was an Art Director for a long time and writing a concept takes a bit more time than that, more so when you factor in re-writes, and approvals, ect. Also consider this isn't your typical film, it's being used in a never before tried sim (at the time), imagineers would have been the writers, and they make pretty good salaries last time I checked.
Point being, it more than likely took weeks/months to concept and develop before they arrived at what we see on screen today.
Your also assuming the state tourisim board cut them a break, I shoot a lot in California and I would be very surprised if they cut any breaks, considering it is Disney they might have even hit them harder. Everyone in CA charges a location fee, a permit fee, a city fee, a state fee, a national park fee, park monitors, park rangers not to mention safety things like fire patrol, ect. California is hip to the drill.
Another thing you might have overlooked is the F-18 hornets doing the fly over in death valley, (or the chopper taking off the deck of the USS Stennis, that took some dollars too) ... those planes aren't cheap to stage, most likely they came from Lemoore in Northern CA and that is not a cheap flight. The military may have worked with Disney on this but they still would have had to pay something, if not at the very least fuel.
Dont forget all the talent and extras, plus the stunts.
You see 13 separate shots in the final film, but as producers you and I both know (or should know) that you shoot a ton more footage than what typically ends up in the final edit.
I would stand by the figure of 15 to 20 million but would love to see the final budget in any case.