20 Things You Didn't Know About Saw

James Wan and Leigh Whannell could only do a handful of takes of each shot since they were always against the clock. When they were editing the film, they realised they missed many crucial moments. For example, there was no clear shot of Sing entering Jigsaw's room nor was there a shot of him falling when he was blasted by the shotgun. Because the actor, Ken Leung, was unavailable for a reshoot, Wan had no choice to shoot the scenes with Whannell standing in for Sing. Wan shot these scenes in close-up so viewers wouldn't notice Sing was played by a different actor.

Pretending to be another actor is quite tricky. Do you know what's trickier? Pretending to be an actress! When Wan realised there were key shots missing for the Reverse Bear-Trap scene, Whannell had to stand in for Shawnee Smith's character, Amanda. Many of the close-ups of Amanda's hands are actually of Whannell's. He wore a wig so his shadow would resemble a woman's.

After you learned his, you really want to watch the film again to try and figure out which shots have Whannell playing Sing and Amanda.