User blog comment:Ḡwẵine Ḹٍٍkƨ Ĺiĸe Ͼềлȑềd/WORST plot hole in the HISTORY of 'Merlin'/@comment-4916403-20121014212601/@comment-4623180-20121017121932

Wasn't it when Cerdan was killed, Mordred screamed, smashing the mirror?

But you know, perhaps Gwen may have thought it was Cerdan's death that caused it...

I don't think we'll ever find out unfortunately.