I know this has probably been mentioned before but I noticed in one episode Kramer went on this hilarious rants about Coma's, in a season 3 episode ("The Coma"). But then in season 8, in "The Comeback", he knew nothing about them.
Season 3: he says if someone doesnt come out of a coma within 48(or was it 24) hours, that everything of theirs is up for grabs.
Season 9: Kramer watches a movie and is amazed when he finds out it's possible to come out of a coma.
but then again, there is another inconsistancy : I referred to the second even as happening in season 9, when it actually (as I stated earlier) happened in season 8. So I guess nobody's perfect..)