So there are two Wonderland Caves.

The one in SD and the one in Arkansas.

Not sure why the website for the Arkansas one has a video of the Sturgis cave or a telephone number to Beverly Hills.

Meanwhile, found this good article on some more history about the Arkansas cave:

http://www.uatrav.com/the_companion/article_b3454ec4-c1ac-11e3-a745-001a4bcf6878.html