Free Willy is a film that Homer saw at Springfield Palace Hotel.
Willy is an orca and while he tries to be free by jumping out of his enclosure, he doesn't make it and crushes the boy who tried to help him.
When Homer was at the Springfield Palace Hotel, during a deadlock while on jury duty, he saw the film. He watched the directors cut and didn't like it.
 Behind the Laughter
Free Willy is a real movie.
In the episode "Treehouse of Horror XI" the film was referenced again when Lisa freed King Snorky from its basin by encouraging it to jump out. While Snorky does this it hits Lisa in the face with its tail.