5. Source Code
For about 95% of its runtime, Duncan Jones' Source Code is a wildly imaginative sci-fi film about a man given one last chance at life. With his consciousness transferred into the reconstruction of a man on-board a train that explodes (that's a mouthful), Captain Colter Stevens (Jake Gyllenhaal) manages to save the day and even get a cheeky kiss off Christina (Michelle Monaghan). When Stevens' time runs out (he's allowed 8 minutes inside it), the source code freezes, and it seems like the film is going to end on a thoughtful, meditative climax with Colter kissing Christina, this being his final memory, forever locked in time. Instead, a few seconds later, the source code gets jump-started, for Stevens has actually somehow managed to create a parallel universe which he can now inhabit. It's a happy ending that comes out of nowhere because a) a freeze-frame ending would have been far more affecting and b) he is still inhabiting the body of someone who is not him (and Christina is still not aware of this), which is really damn creepy.