Magicians have used suggestion, mild hypnotism almost, to what they call "impress" the card they want a person too choose for many years. Who knows how many cards were missing from the deck? There could have been !0 cards missing. All he has to do is choose one of those. Blaine asks him to pick a piece of fruit, then he asks what the card was. Blaine has a deck of cards in his pocket that are marked. When Ford names the card, Blaine riffs throughout the deck & grabs the card he needs. Watch the weird way he hold he holds the knife, & then makes sure Ford is holding on to the Orange when he cuts it. Magicians are masters of sleight at hand. He makes the cut in the orange & inserts the folded card & then gives the Orange to Ford.
I'm stoned.