So, a mystery: I know someone who claims to have seen Mr Macintosh, even though he was supposedly never actually implemented.

This was maybe 2000 or so. My dad's lab assistant had been working on one of the Macs when he said that a small cartoon man abruptly appeared on the screen, waved at him, and then vanished.

It sounded exactly like how Jobs described Mr Macintosh. But the original Mac people never added him, and I've never heard any evidence that Mr Mac was hidden anywhere else, either.