Ratatouille Easter Egg - Dug from Pixar's Up in Ratatouille

Early on in the movie, Remy (the main character) is running through various apartments after climbing out of the sewer. At one point, he runs into a dog who starts barking at him. The dog is the character Dug, a talking dog from Pixar's later movie Up (2009). Pixar is known for including references to their upcoming films, as well as references to their previous films.