I can recall an episode of The Simpsons in which Bart and the bullies go to a bully meeting. In this meeting one that seems to be the boss starts a speach but is interrupted by another bully who hits him with a sling and then accuses Bart. The bully have now to go back to Springfield traversig the territory of other bullies.
This is the plot of the movie The warriors.
I recall this episode now, but there are many other examples, so I wonder: do the creators of the Simpsons have to pay copyright to the film maker for copying the plot of the movie?