 Everyone is supposed to wear bungee jackets, in case the rink were to break or stop working - which would have never happened intentionally.But Tally, Zane and the Crims stage a breakthrough by pouring vodka on the ice to reduce freezing temperature, and then putting stress on the ice causing it to break during the firework display (the safety fireworks are designed not to hurt people).The Crims act innocent, but Dr. Cable realized it was planned (there are no mentions of anybody else noticing the Crims never got in trouble).