We first noticed the “Project M” naming convention used on a permit just days before it was announced that Mickey and Minnie’s Runaway Railway would be replacing The Great Movie Ride. Today, we know what the “M” stood for, Marceline. A closer inspection of the following photo in the Runaway Railway display at Walt Disney Presents, reveals the codename in the project path on the Imagineers computer.
Marceline, of course, is the hometown of Walt Disney. It would only be fitting that an attraction centered around Walt Disney’s iconic character would bear the name of his hometown roots.