Pixar loves to have little hidden things in their movies that go to other Pixar movies. In Finding Nemo, when nemo is in the fish tank and looks around the office, there is a Buzz Lightyear toy. In Monsters Inc, Boo hands Sulley her toys and one is a clownfish (Nemo). Also in A Bug's life at the end when Randell ends up in the trailer, there is the Toy Story pizza planet truck that is seen in all 3 Toy Story movies. And there are others, you just have to look.