Use the "Event" button on the following stages to get the corresponding effect:
STAGE - EFFECT Woods - Rain slows down zombies; torch is extinguished and cannot set zombies on fire, but can still scare them; zombies that are already on fire remain burning. Cemetery - Divine ray kills zombies. Suburbia - UFO abducts zombies. Drive-In - Plays music that makes zombies dance briefly. Military Base - Line of TNT drops down. Secret Lab - Three lasers rotates around the middle of the level that will kill everything.