Missing Card Illusion

game

Count the number of small cards. There are 13. Now reverse the positions of the large cards A and B. Just drag and drop them. The large cards will "snap" into place when they are nearly lined up. Now count the number of small cards again. Now there is only 12! Where is the missing card? Can you explain it?

Publisher: Sandlot Science
Language: en
Year: 2002