 Frank Thomas (I) (qv) and Ollie Johnston (qv), two of  Walt Disney (qv)s Nine Old Men (his team of nine supervising  master animators from the classic era of animation), provide voices  for their own caricatures near the end of the film. They also  appeared in and provided the voices for the train engineers in  _Iron Giant, The (1999)_ (qv), which was also directed by  Brad Bird (I) (qv). This is not the first time Pixar Animation  Studios has included references to famous animators in its films  (see the trivia for _Monsters, Inc. (2001)_ (qv)).