Revealing mistake: John Kramer's chain first goes on the side of his stomach, and then it's on his backside... impossible, otherwise the chain would split him. (01:35:47)
Revealing mistake: When Jason is getting stabbed to death, there's a quick 2-second shot showing him being stabbed repeatedly in the stomach, with part of his intestines hanging out. But if you pay close attention, there's no actual damage occurring with any of the stabs, revealing it's just an effect. Likely either a collapsible prop knife or a CGI knife being stabbed into him.
Revealing mistake: Boyd brought Dr. Mackles to the location where he escaped the police hunt. Meanwhile, he rummaged through the rest of the place. In a closet, he found a newspaper with an article that talks about the evil South African CEO. In the first paragraph, because the rest is filler text about a completely unrelated topic (the answer about an inheritance question from the advice column of the Moneywatch website). (00:58:50)