Can't delete podcasts from library

I found a few old podcast episodes still sitting in my iTunes library. The actual files were deleted months ago (I checked...they're definitely gone), and the episodes aren't showing up with my other podcasts. But for some reason, when I create a smart playlist looking for the word "podcast", I still find these library entries. I've tried searching in Music and Podcasts, but it doesn't find them.

What I'm trying to figure out is how on earth to delete these library entries, since I can't actually find them except when using a playlist? Every time I plug in the iPod, it warns me that it can't find these files...it's getting annoying. I even tried mapping the entries to some other file, but I still can't find the entry anywhere except in the smart playlist, so still can't delete it.

Thanks in advance for your help!!