The opening and closing credits show a picture on the screen that corresponds with whatever credit is being given ("Music by" is accompanied by a man playing a violin, "Written by" has a Mark Twain-inspired writer type holding a book with "Bonanza" written on its cover, etc.)
In the opening sequence, when the actors ride on their horses towards the camera and are introduced, the order in which they are introduced is never consistent - this was most likely done to prevent a single actor from becoming the "main" star of the show.