If Mad Men's sixth season taught us anything, it's that, as viewers, it's entirely possible that we might need to take a step back from the shows and movies we love so dearly. But, before you swear off cultural conspiracy theories for good, we invite you to jump down the Pixar rabbit hole with Jon Negroni, who posits that all of the company's movies are connected.
Basically, his theory is centered on the notion that there's a struggle between animals, inanimate objects, and humans occuring over time within the same dimmension. The crux of the theory is that the doors in Monsters Inc (which Negroni classifies as the most futuristic on the Pixar timeline), aren't portals to an alternate dimmension, but rather a means of traveling through time.
When Boo makes her way into the future via the door, Negroni suggests that she learned to time travel and has since been navigating her way through time on her own and, eventually, became the witch in Brave (the oldest movie on the Pixar timeline). This would explain all of the easter eggs littered throughout the Pixar universe (and why all of the easter eggs in Brave are in the witch's workshop.
It's a crappy Friday afternoon in the middle of July. You owe it to yourself to waste the rest of your work day pouring through Negroni's theory and debating the logistics of a world where A Bug's Life is actually a post-apocalyptic portrayal of Earth further along the timeline than Wall-E.