I may be behind others on this one but I recently stumbled onto the site called http://www.pixartheory.com . If you’ve never been to it before i highly recommend you check it out as it shares a fascinating theory that all of the Pixar films are indeed related. I love fun theories like this and it looks like they really have a good one on their hands here. Definitely check it out and let me know if you buy into the theory in the comments below!