Many modern productions use projections of images or films, along with lighting fixtures like strobe lights and black lights. Lighting designers may also use gobos, which are flat pieces of metal with shapes cut out of them. A gobo goes in front of the theatrical light and casts specifically-designed shadows on the stage. A director would use a gobo cut with the shape of tree branches to give the impression that actors are in a forest.
Weather effects such as snow or fog enhance the setting of a scene in a play. Snow machines create the illusion of falling snow onstage. When a director uses a fog machine, she can instantly achieve a spooky or dreamlike feel to a scene. Also, bubble machines can add a dreamlike quality to a flashback in a show.
A show can have pyrotechnics without actually lighting anything on fire. Using a special rig made of colored lights, a fan and some fabric, an effects designer can create simulated flames on the stage. For real flames on a stage, designers use flash pots. Flash pots are made of metal and hold flammable powder within them. Stagehands light flash pots for all sorts of effects: bright flashes of light, leaping flames, colored smoke and loud explosive noises are some examples.
Some productions call for little more than someone yelling a line from backstage. Most shows, however, require a more complex sound system, with a sound board and various speakers throughout the theater. Sound designers may choose to record their own sound effects or purchase pre-recorded ones. Some directors prefer sound effects to emanate from different areas of the stage: for instance, a director might prefer the sound of a telephone to come from the telephone itself rather than over all the speakers in the theater.
Different shows provide challenges to the production teams in terms of special effects. Many shows require actors to fire guns onstage. The actors would use prop guns that fire blank bullets, and an actor on the receiving end of a gunshot blast would burst a blood pack. A stagehand could rig an actor's costume to smoke for a performance, using a fog machine. A director could choose to use a wind machine to make it appear that an actor is standing on top of a building.