During the filming of ‘Now You See Me’, Isla Fisher’s escape tank scene went horribly wrong when her chains became tangled. She managed to get free and escape, but the experience goes to show how dangerous this stunt is. Houdini was the first to perform it and for years, no one could imitate him. As you could guess, the cuffs are rigged so that when the curtain covers the tank, they can be easily taken off the ankles and wrists, and closed back up as if they were never opened. Then, they lift the actual top (not the locked one) to escape and appear somewhere else on stage when the curtain is lifted to reveal an empty tank. They may seem like obvious lock tricks, but the illusion requires an abundance of skill and speed.