Subscribing doesn't involve the Store updating because your iTunes application is accessing the media file directly (and the feed). Something odd is going on, possibly with cacheing somewhere along the line. Don't worry about the Store page: check your file by subscribing afresh, and also by entering the media file URL in Safari (rather than FireFox) where it should start playing fairly quickly while continuing to download, and show the correct duration. Currently everything is still seeing the old version of the file.
I just checked it again: also I downloaded that and the previous episode from the media file URL. The previous episode started to download a file of a suitable looking length (and it plays correctly in a browser). The latest episode downloads a file of only 11.9MB. This is the URL - try downloading it yourself (control- or right-click and choose 'Download linked file' or equivalent).
http://colliderscope.jellycast.com/files/audio/colliderscope%2010.11.2012_mixdow n_128k.mp3
So you still have the original file at that URL. You need to go into the server, delete it completely, and re-upload the proper file: I should change the filename and amend the feed as I suggested to be really sure.