How Franco Cut Off His Arm, and Other Movie Secrets

(Newser) – James Franco's self-amputation (using a blunt pen knife, no less) in 127 Hours is apparently so realistic that audiences are fainting and vomiting at the sight of it. How'd Hollywood pull that off? At first, by using makeup to create a decaying arm, explains one of the film's makeup artists. But when the arm actually gets severed, prosthetic arms and tons of movie blood came into play. The Daily Beast spills the beans on a dozen other cinematic secrets:

• One actor playing twins: To create the scenes that included both Winklevoss brothers in The Social Network, Armie Hammer acted the part of one while a similarly-built stand-in played the other; Hammer's face and voice was then digitally superimposed onto said stand-in's face.
• Smoking crack, and doing other drugs: To portray a teacher addicted to drugs in Half Nelson, Ryan Gosling smoked "crack rocks" made from dyed broken porcelain (from a coffee mug), put in a pipe with a pinch of tobacco to create smoke.
• Binging on food: Julia Roberts ate her Italian feast in Eat Pray Love, but to film Harold & Kumar Go to White Castle, Kal Penn worked his way through 30 sliders with the help of a spit bucket.