Myst III: Exile Unlockable: Character gallery
In the Tamahara Age on Atrus’ desk hold “~†and select the picture of Atrus and Catherine to see the character gallery.
Myst III: Exile Easter Egg: PEZ
In Saavedro’s home near the hammock. Look around and hold the “~†key. This will bring up a zoom in option. If you zoom in you can find a PEZ dispenser with the initials MEB on it referring to the lead animator of the game.