Let's say you're getting ready for your next trick, you do a nice smooth card dribble, but a slight breeze passes by and causes a few cards to flip over. No worries, just finish the dribble, square the deck, and spread the cards on a table. Take out the three cards or two cards or how many cards (hopefully not more than 5). Now instead of having done a normal in-hands card spread for them to select a card, have them select one of the cards that flipped over.

Let's say you have the selected card controlled to the top or the bottom. You once again do a small flourish. Then suddenly, you accidentally drop a packet of cards. Uh oh, what do I do?
Say "Are any of those your cards?". While they're looking, palm the selected card to your pocket. Then continue to drop packets or reveal packets in magical ways in attempt to find their card. Once you run out of cards to try to reveal, it will look as if their card has vanished. You have their chosen card in your possession; You choose how to properly reveal it.