The Nope standing shoe is one of the most puzzling and intriguing aspects of the horror movie. The latest from Get Out director Jordan Peele, Nope primarily focuses on an attempt to capture a UFO dubbed "Jean Jacket" on camera, yet a key subplot adds to the mystery of the movie. The backstory involves an incident on a sitcom that Ricky "Jupe" Park (Steven Yeun) starred in as a child actor in which a chimpanzee performer attacked the cast. Amidst the chaos, young Jupe sees a shoe standing on its own in Nope's flashback sequence.
https://screenrant.com/why-shoe-was-standing-up-in-nope-movie/