In many DVDs and Blu-rays today, the special features include a blooper reel. It's a relatively modern practice considering these takes ruined by a laughter, someone flubbing their lines, or a crew member in the shot cost next to nothing to keep and store nowadays thanks to video. At a time when each kept take meant extra money for developing the film, the director was careful to keep only the takes he figured he would actually use in the editing.So...
