9. You Don't Bring Back A Character For Two Seconds - Saw 3D
This one is possibly the most obvious twist on this list. It was very easy to see it coming that Cary Elwes Dr. Lawrence Gordon character - from the first film - is secretly Jigsaws third apprentice, and has been for years. Although the idea of Elwes ever returning to the franchise had been played down in the press (not least because he had sued the studio for underpaying him for the first movie), as soon as he turned up in Saw 3D it was clear that he was set to play a core role.
And he turned up right at the start, essentially spoiling the film's twist at record-breaking pace. Although the franchise had returned to Saw's iconic bathroom a number of times, Saw 3D opened with an Elwes-starring flashback which set the film's stall out fairly conclusively. What would be the point in that scene if it wasn't relevant later on? The fact that Gordon had been the subject of fan theories for years didn't help, either.