This rule/plot hole has always plagued me too, although the thing that keeps me awake is time zones. And what about daylight savings? Does a mogwai's internal clock automatically spring forward and fall back like my laptop? Don't get me wrong, I love me some Gremlins. Pangaea-sized plot holes don't keep from enjoying awesome stories. They do however keep me from writing great stories. I just can't seem to make myself believe the silliness I write. I've always said that if Gremlins had been my idea, it would have been crumpled up and tossed in the trash before Billy even met Gizmo.