A Sound of Thunder (2006)

Set in a near future where time travel is possible, this is the story of a travel agency, Time Safari Inc. that arranges hunting trips for wealthy customers back in time to hunt dinosaurs. Each trip is carefully planned, with a scout identifying dinosaurs about to die, and then sending the clients back just seconds before, so the course of time is not altered by the kill. However, a nervous hunter, Eckels, steps off the trail and steps on a butterfly. The historical repercussions of the death of a single butterfly leaves the hunters to a future that's not quite the one they came from.

Official website: http://asoundofthunder.warnerbros.com/