It looks like we're truncating the feed to only show so much, which is fine, because even if we didn't iTunes would. I forget the exact cap, but they only allow so much information in a feed before they ignore it or cause it to fail.
Looks like your best bet is to buy the archive CDs, or go to the first episode (
http://escapepod.org/category/podcasts/page/40/), run it from the page or download it manually, and work your way forward.