About halfway into a club game where there are 9 rounds, 3 boards per round, one table finishes up board 25. E/W move board 25 to the bottom and remove their cards from board 26, sorting them, etc. A few seconds later, North moves board 26 to the bottom and N/S remove their cards from board 27, sorting them, etc. On board 27, south is dealer and opens 1♣. West, holding the cards from board 26, bids 2♣, michaels, and north bids 2♦. East goes into the tank for about 30 seconds and then all the players realize at about the same time that the card backs are different colors. I assume it is appropriate to call the director? Who should call the director and what should the director do? I would put this in the simple rulings forum but there are followups depending on what happens next.