Lovely movie, but one small part sticks out.
While I made the connection that the janitor was the grandpa robot, I realized that earlier on in the flash the two eyes were switched, and the eye with a circle through it only had one half, though this could have the purpose of expressing emotion. This all but confuses the observational viewer when the connection is finally made, sadly :(
This is the only criticism I have for this movie, though. Everything else was beyond perfect, including the graphics, sounds, effects, animation smoothness, and even the storytelling. This movie in no way even comes close to the already high expectations I had for this movie, despite its place in the top 50 of all time. This is definitely something I would love seeing as a full film, if funding magically appears.