Pixar movies are full of Easter eggs and references to past and future movies, but Ratatouille went a bit too far with a dark Easter egg that connects to one of Pixar’s biggest box-office hits. Pixar is now a powerhouse in the world of animation, and it all began in 1995 with Toy Story, the first entirely computer-animated feature film. Since then, Pixar has brought a variety of stories exploring different cultures, settings, and worlds, and not all of them have been human. Falling into that category is Ratatouille, set in a world where rats have the same aspirations as any human.
https://screenrant.com/ratatouille-dark-easter-egg-finding-nemo-reference/