3. The Grand Hall scene in the Haunted Mansion (Disneyland, Magic Kingdom, Tokyo Disneyland, Disneyland Paris)

Image: Disney

The experience: The Grand Hall plays host to a dinner party, complete with birthday cake, music and dancing ghosts that seem to glide gracefully around the dancefloor. How it works:This is one of the most famous Disney effects of all, but the company didn't invent the technique. In fact, the "Pepper's Ghost" illusion is based on a term coined in the 1800s by a professor of chemistry at the London Polytechnic Institure. The ghosts that you see dancing and celebrating in the Grand Hall are actually animatronic figures in black rooms above and below the mezzanine that your Doom Buggy is on. There is a gigantic pane of glass between the riders and the Grand Hall. A light source shines on the animatronics below, which reflects them off of the glass and makes it appear as though they’re actually in the Grand Hall. You can even test this method for yourself, by following the steps below:

1. Take a small to medium sized box and line the inside with black material.
2. Place a light-colored object in the box.
3. Remove the glass from a picture frame.
4. While standing behind the box and holding the glass a couple of feet in front of the box, use a flashlight to shine light into the box (a second person makes this all a bit easier, so get help if possible).
5. Your object will be reflected in the glass in front of you! Now, imagine a tiny track of buggies passing in front of that pane of glass and you’ll get a clear idea of how Pepper’s Ghost works for the Haunted Mansion.

At 30 by 90 feet, the Haunted Mansion has the largest Pepper's Ghost setup in the world. The Disney team actually made a mistake when setting this scene up. The dancing animatronic figures were created to have the men lead but, when reflected in the glass, the women lead.

2. The loooooong corridor in the Twilight Zone Tower of Terror (Disney's Hollywood Studios, Walt Disney Studios)

The experience: As they climb in a service elevator towards the top of the Hollywood Tower Hotel, riders witness a scene in one of the hotel's corridors in which ghostly figures of former hotel guests beckon them into the Twilight Zone. The spirits are then zapped by lightning, and the room transforms into stars and empty space, with the exception of the window at the end of the corridor. This then smashes. How it works:There are really two separate tricks at play here. The first one is "Pepper's Ghost", as used in the Haunted Mansion's Grand Hall scene. The ghostly figures are projected via a mirror onto a diagonal sheet of glass, giving our brains the impression that they are right in front of us. The corridor is made to look longer than it really is using a forced perspective technique, with the elements at the far end being smaller than those that are closer to riders. In fact, the corridor is 10-feet-high at the front, and only 4-feet-high at the back. The Pepper's Ghost trick is used once again to show the window morphing and smashing, in combination with fiber optic lights that are used to represent the stars.

1. The "clouds" in Peter Pan's Flight (Disneyland, Magic Kingdom, Tokyo Disneyland, Disneyland Paris)

The experience: As they fly over London below at night-time, guests can see clouds obscuring their view of the city below. How it works: This one really is ridiculously basic. The lights that you seen in the city below are simply fluorescent dots on the floor, with black lights shining on them. The moving lights that represent cars are dots of paint on a chain, which resembles a long, thin bicycle chain. The clouds? They are white plastic garbage bags lying on the ground! In the light, this is obvious - but under the black lights, the effect is really quite convincing.