he somehow planted that card under the menu before he set it down and stabbed it. if you look when they're spreading the cards, there is no card in the area where he stabs that is just sitting on top of all the others, but when he stabs and pulls the menu out, that card that he stabs was obviously placed on top of of the rest. see how it's just sort of sitting there on its own?
and then the reason he asks so many people to look at the card is to give his dude behind the camera enough time to look for that card in another deck and slip it over to him.