The Hidden Mickey has become a phenomenon among Disney fans and the Walt Disney Imagineers who design the theme parks. You can find Hidden Mickeys throughout the Disney theme parks. Some are obvious, while others are very well disguised.
While there is no official statement on the first Hidden Mickeys in the theme park, multiple sources state that the Walt Disney Imagineers first developed the concept for the Epcot Center theme park in Walt Disney World® in Florida. At the time, the Disney executives didn’t want to have any Disney characters in the theme park, instead focusing on the futuristic and worldwide theme. To have a little fun, the Imagineers decided to slip the silhouette of their favorite mouse into areas throughout Epcot.
After the Hidden Mickeys were discovered by guests and Cast Members, the concept began to spread. The management decided they liked the wholesome concept and encouraged the design team to add Hidden Mickeys to all future projects. Over the years, many more Hidden Mickeys have been added throughout the theme parks.
There are ways to take the randomness out of searching for Hidden Mickeys. If you are interested in this concept and want to see more of the Hidden Mickeys during your trip, check out "Disneyland's Hidden Mickeys" by Stephen Barrett. In this book, you'll find clues and information on many of the documented Hidden Mickeys throughout Disneyland Park.
You can also visit his website for complete photo documentation of numerous Hidden Mickeys throughout the Disneyland Resort, Walt Disney World®, and even the Disney Cruise Line!