Ha! Strange that this is a new find. I got more than one "easter egg" like this simply by writing a letter to Nintendo America back in the day, and asking for help. They'd usually write you back with suggestions like this.
The one time I ever called Nintendo was when I stumbled across the Chris Houlihan Room in Zelda for SNES—and they didn't know what I was talking about. I was half disappointed and half impressed to have stumped a Game Counselor. I wanted to know what the hell I had found!
