When Walt put Imagineers Rolly Crump and Yale Gracey in charge of creating the visual illusions for the attraction, they intended to make the "Museum of the Weird" into a separate section that guests could walk through and discover illusions from around the world. Guests would be able to see transparent ghosts and other apparitions, utilizing the Pepper's Ghost technique used in the theater since the early 1800s. Crump and Gracey were eventually given an entire warehouse to house their developments and one evening forgot to switch off the mechanics before leaving for the day. The cleaning crew was met with surprise as Crump explained, "Once, we got a call from personnel saying that the janitors requested that we leave the lights on in there due to the creepiness of all the audio-animatronic ghosts and such. We complied, but put motion sensors in the room that would extinguish the lights and turn on all the ghost effects when triggered. The next morning, we came in and found all the ghost effects still running and a broom lying in the center of the floor. Personnel called and said that the janitors would not be back."