i've never seen that before...I've been waiting for screenies of this little "secret". After the survival mode thing, my confidence in hidden features has been revived somewhat. I say we reopen the debate over wtf these little white things are now.
that thing is liu's fireball without the fire trail... some times they freeze and stay there a little bit...it hapens a lot (to me) when i'm playing in ko-op. i think it's just a bug... :?