A still from "Riders of Justice." (Courtesy Rolf Konow/Magnet Releasing) It begins with a stolen bike. Then a car won’t start. A stranger offers a lady his seat on the subway and suddenly we’ve got a story. For you see, that subway train is about to derail, killing not just a young girl’s mother but also a key witness in the upcoming trial of a feared criminal. In the hugely entertaining action-comedy “Riders of Justice,” this curious chain of events is obsessively investigated by three unemployed probability scientists who determine — not without a fair amount of squabbling amongst themselves — that the crash was no accident. But, as the movie keeps reminding us, if you stare at something long and hard enough, patterns are naturally going to appear, and how much we really believe anything often depends just as much on evidence as upon how much we want it to be true.