AJAX problem in CiviCase - Administer Case Types
OK, I found the problem. It was the same issue as reported here. It wasn't a CiviCRM problem at all. The JavaScript errors were caused by the K2 component, which alters the HTML output after CiviCRM does. K2 was passing text containing quotes (specifically 'prefix="og: http://ogp.me/ns#"') to JavaScript, so these quotes ended up unescaped. More info here. The solution was to apply this patch to K2 (or, in my case, to remove K2 altogether, since we decided not to use it).