The audio file is at
This plays in Safari (though it was quite slow to start) but neither iTunes when subscribing nor FireFox would play it. An attempt to open it in FireFox said it ws trying to connect to www.shannon-kennedy.com
The image URL is
This wouldn't open in Safari but from the 'Source' view in FireFox I got an HTML page with an iFrame.
So something very messy is going on at your server and you will need to take this up with the people running it.
This has certainly made it work, and the good news is that your server does appear to be handling 'byte-range requests' (the method used by iPhones and a requirement for acceptance in the Store). The only other thing is that it's all downloading awfully slowly - some seconds for the image. This shouldn't actually prevent you being accepted, though anyone playing the episode in the Store may have quite a long wait before anything happens.