Pianonrd

I am trying to print a little hat (not 3D modeled by me, found on thingiverse). It renders it normally, but when I go to preview there appears to be a hole. When printed it ended up with a hole. As you can see it is rendered fine, yet when in preview mode, it shows a hole for supports or something? I am fairly new to this so some help would be appreciated. The Thingiverse page cowboy_hat_for_thumbman.stl