Is there a contradiction between John 16:5, where Jesus says that none of the disciples is asking him, "Where are you going?" and John 13:36, where Peter asks Jesus, "Where are you going?"

I argue that there isn't. Watch (or listen) to find out why.

Plus, even if this were contradictory, it would hardly be evidence for a "seam" left by an editor. This is so obvious that Raymond Brown has had to argue that it's evidence for an editor who doesn't edit, due to his reverence for his sources, which is rather like a blue elephant that you can't see.