I just realized: Since this is marked as computer-animated, what if it is stop-motion computer animated? Maybe not 100%, but I mean, we get graphics like this a lot these days. What if they made a virtual set, set up with all the amazing graphics, scans and models of different pieces, and took stop motion images to pass through into the movie to keep the realistic feel? It would make changing out parts and such easier...
Just my thought on why it'd be marked as computer-animated. Maybe a part of it like that?