When Cloud falls from the Mako reactor into the old church where Aeris is, I believe that before he comes to someone in his mind is saying something about when he was younger he would have only had skinned his knees or something like that. I know that throughout most of the game Sephiroth is the one talking to him in his head but how would Sephiroth know about Cloud's youth? Not even Cloud remembered his own youth... correctly anyway.
Sorry for yet another Sephiroth question.