I believe I may have found a bug with SharePoint 2013 / Office Web Apps 2013 Document previews in the search results...
We have ADFS authentication configured for our web application on the Default zone and have extended the web application to use Windows authentication on the Internal zone for crawling (we want the default authentication to be ADFS, but search requires Windows authentication to crawl content so that is why we had to extend it). All worked well and we were able to get the search results to display correctly by using Server Name Mappings, but when hovering over a document in the search results, Office Web Apps does not recognize the Server Name Mapping and tries to load the preview with the Internal zone URL (which is only accessible on the server).
Is anyone else experiencing this issue, and if so, could you help me out? Thanks!