Visible crew/equipment: When Don talks to David about his priorities and the importance of finding Rachel Abbott's car, right after David tells him that the car is not turning up, we can see the reflection of the moving boom pole and mic on the glass door.
Visible crew/equipment: After Charlie tells Alan that he and Amita have a lot of work to do and that Alan's hovering over them, when Alan walks away from the table we can see the actor's tape marks on the floor where he had been standing, and also more blocking tape on the rug and kitchen floor.
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.
If you bet against the roller in craps, your odds of winning are about 49%, which is as good as you get in Vegas. The point he's making (though it's pretty obscure) is that if you're going to bet, you may as well bet on something where you have a slim chance of winning, as opposed to the lottery, where your chances are basically 0.