Indiana University Bloomington Library has an incredibly comprehensive guide to copyright, including some particularly useful sources regarding copyright for filmmakers. We won't reinvent the wheel. They have sections dedicated to "Original and Adapted Screenplays," "Clips," "Music," and "Buildings, T-shirts, and the Like." Please view this highly useful resource here:
"Copyright for Filmmakers." Copyright, Indiana University Bloomington, accessed April 24, 2023.
“Film and Copyright.” Film History, vol. 19, no. 2, 2007, p. 107–108.
"Copyright Term Extension Act." Wikipedia, 8 Feb. 2023.