Actually, Canon farms out the work to the Nikon plant, that is why the demo is a virtual demo, not images of the real plant.         

Humm..maybe I just made this up...

Actually, quality control of glass production is extra critical here for either Canon or Nikon. Critical also  for auto glass..yeppie, windshields and auto windows, btw.  A Dupont autoglass  plant I know of lost its glass making contracts because of old equipment and unwillingness to update by the union workers, fearrful of lost jobs.  Well, all the jobs were lost and the speck free glass for autos was done in Japan, glass qualities Dupont could not produce at the time with current tooling.