It's hard to beat a fun ride on the Tower of Terror but you have noticed a lot of junk in the room you go to right before exiting and wondered why it's all there. Some of this junk actually does actually mean something and in this case, it refers back to a classic Twilight Zone episode.
The slot machine is a reference from a Twilight Zone episode called "The Fever" where the slot machine talks to the man playing it, and taunts him. This same slot machine is also in two other Twilight Zone episodes. "The Fever", from the first season of the Twilight Zone, stars Everett Sloane as Franklin Gibbs who goes to Las Vegas with his wife because she won a competition. Franklin hates gambling but he agrees to go on the trip. While at a casino, Franklin is given a coin by a drunk man who makes Franklin use it in a slot machine. Franklin wins and tells his wife that they should keep the money and not lose it back like the other people. Franklin goes on to lose a lot of his own money in the machine and for the rest of the episode is haunted by what he thinks is the slot machine calling his name.