The enemies you hadn't seen were from the Japanese version. The robed zombie may have been in the US version's 2nd quest, but i'm not sure. I know the flying skull was, though. The wererabbit was the Japanese version's Hunchback/Fleaman. The zombie with its arms down (2nd from the left at the very top) was the original Japanese zombie. Why they changed it I can't say, maybe they just liked it better that way.