Many movies don't have the "opening credits" at the start of the film, Star Wars a good example of it but there are scores of others. The credits that would be at the start of the film are shown first at the end of the movie in a different style from the ful credits because they are those "main credits" and the ones those rules apply for even if they appear at the end of the film. Deadpool had those. Animated with boner jokes. They are the start of the film credits they just appear at the end of the film.