Real world article
(written from a production point of view)
An outtake is a filmed failed version of a scene. Unlike a deleted scene, which is removed for creative reasons, outtakes are not included in the final product due to errors made by performers and crew, either accidentally or on purpose as a prank.
Outtakes are sometimes assembled into reels for the enjoyment of the cast and crew. Some of these scenes are also included on DVDs as part of special features.