I had actually stopped renting movies just to find Wilhelms. I think I’d reached the bottom of the barrel and anything else I need to rent is really unappealing. So it was a great surprise to find one in Juno of all places!
Juno isn’t the first film to include the Wilhelm in a movie within the movie. I believe Poltergeist, Win a Date with Tad Hamilton, and an X-Files episode all use this trick to fit in a Wilhelm. In Juno though the clip with the Wilhelm is actually named - The Wizard of Gore, which Netflix happens to have and is in my queue. The scream occurs in Chapter 13 of Juno.