I think this is a bug in Popcorn Maker, to be honest.  Not being able to deal with a 404 or anything else that isn't a 200 means we'll often have timeout issues, which we've known about in Popcorn Maker for a long time.

I think we should patch Popcorn Maker to be smarter about how it does this request, see http://www.haykranen.nl/2011/02/25/jquery-1-5-and-jsonp-requests/ for one solution that includes a timeout and will trigger an error handler.  CC @ScottDowne