Poster for the film 'The Butterfly Effect', 2004.

'The Butterfly Effect' is a 2004 American science fiction thriller film written and directed by Eric Bress and J. Mackye Gruber, starring Ashton Kutcher and Amy Smart. The title refers to the butterfly effect, a popular hypothetical situation that illustrates how small initial differences may lead to large unforeseen consequences over time. The production shot four different endings, with a different one being used for the intial release and the later director's cut.