At the 2012 Summer Olympics opening ceremony , an effect similar to a card stunt was achieved by mounting a small panel with LED lights next to every spectator seat in the stadium , effectively turning the entire seating area into a big display for the audience seated on the opposite side . The show 's producers , rather than the audience , controlled the light panels . Card stunts involving large numbers of people have become a standard part of similar celebratory gatherings in countries such as North Korea
2012 Summer Olympics opening ceremony
2012 Summer Olympics opening ceremony
Card stunt