For context, these were outfits that were worn at Tomorrowland in Disneyland during the grand opening of Star Tours. The reason they weren't wearing outfits based around Star Wars was probably because the franchise didn't have the presence in the parks as they do now, as Star Tours opened at least four years after Return of the Jedi. As for the rainbow designs of the space suits.... I don't know.

Mickey, Minnie, and costume designs are to The Walt Disney Company