If you really want to try to track down the manufacturing, the list starts at http://www.canon.com/corp/list03.html. There are four partners/subsidiaries in Japan and one each in China, Malaysia and Singapore. Canon was part of the now defunct Fuyo Keiretsu which would give a hint towards part suppliers.
When I worked in Japan (at a different company) there was a Canon factory near us on the Tokyo periphery. I remember meeting a foreigner who worked at the factory and having a nice chat on the train. Unusual because Japan hires few outsiders.
Maybe I should try to look him up and ask about the 1DX.