Dirty Bomb - S1-E10
Factual error: Season 1, Episode 10, "Dirty Bomb": The opening figures refer to "500g of Nuclear Material." These are the wrong units to determine the hazard level in a radiological sample. The "Curie content" describes, roughly, how much radiation will be given off, and is not tied directly to the sample's mass. 500g of Cesium-137 (the isotope being discussed in the episode) could well be less radioactive than 1g of a different isotope.
Dirty Bomb - S1-E10
Continuity mistake: When Charlie is writing the result of the calculation for the first time he writes "25,600", but when the shot changes he finishes writing "25600", without a comma.
Answer: Craps is a casino game where players bet on the outcome of a dice roll. It deals heavily with probabilities and is a favorite of math experts like Charlie. Whatever the odds, though, your chances of winning are much greater than winning the lottery.