It's possible that:
* The movie title is slightly different. Perhaps it's a documentary, a short film, or an independent production with a different title.
* The year is incorrect. There are several films about Billy the Kid, including "Young Guns" (1988), "The Left Hand of God" (1976), and "Pat Garrett and Billy the Kid" (1973).
Could you please provide more information about the movie you're interested in?