well spotted unsung! "The Wilhelm scream is often used for when a character is plummeting to a great distance, usually falling off a ledge. Its use in the Star Wars films was the beginning of something of an in-joke among some sound designers of the film industry, especially at Skywalker Sound, and Weddington Productions (now a division of Technicolor Sound Services). They continued to try to incorporate it into movies wherever feasible; action movies are naturals, but film sound cognoscenti are particularly impressed when it is used naturally in films such as A Star Is Born (with Judy Garland), The Wild Bunch and A Goofy Movie."