MacBook Pro with Retina display, OS X Mountain Lion (10.8.2)
I think the folder icon in the category head is a bug. I've seen it on occasion also. If you switch to a different view — such as list — then switch back, I think it will go away. For a a while.
As for the items under the "Other" category, I think they are just items that don't have an associated category, however that category is defined. If you want a clear separation of folders, try arrange by Kind.
Why the confusing inconsistency in Finder? 3rd column category header looks like another folder - lacks divider underline and instead uses the folder icon. Why are applications grouped with folders when select 1) Applications & 2) Label as the sort
