well, even M*A*S*H got the song wrong by doing it as "count" instead of "plan" but they got the presents "on" and not "under"
Still, if you look up "new" versions of the song, some are on, some are under, but all are count.
Vince Gill, Mickey Gilley, Martina McBride, Sarah McLachlan, 98 degrees: "on"
Kenney Chesney, Whitney Houston, Lonestar, Brad Paisley: "under"
Jordin Sparks even did it presents "by" the tree
but, really, due to this, it should have reverted to the original. which is "on" - any Christmas Carol book will use on instead of under - do not get me wrong, I like hula best out of all the hosts, but this one was incorrect. Especially since I, personally, had never heard a version which used "under" - and I ain't old.