hi

i´m planning to create (with a friend) a 3d-movie (about 3 minutes long). in this movie will fight homer simpson and mr burns in matrix-style (no senseless violence, no blood, its just a project for university).
the only actors are homer and monty (and they look really good :D), all other (the city-environment) is invented and made by us
the project will be released under GPL

i just want to figure out the legal situation.
does i have to consider something if we create this?