Looks like A LOT of different issues throughout the site. JS isn't working anywhere in showcase at all. You might want to re upload the files again to make sure all the JS files are uploaded. Also, you seem to have an "attachments" issue as there are several broken/missing thumbs. Did you recently move the site from one server to another and not move the attachments images/thumbnails? Maybe rebuilding thumbnails (showcase thumbnails) will fix that part (its one of the Showcase Rebuilds) .
I can't see the site with the XenForo Default Style, so I need to ask... is the Xenforo Default Style behaving the same way? If so, then its most likely some sort of server caching issue (very common issue). If the XenForo style works, but the other style doesn't, then it could be a style conflict (however, to me it looks more like a server caching issue).
Are you using a CDN or Cloudflare by chance? Both of those have been know to cause caching issues that cause problems with attachments and js.