I own a Philips Magnavox DVD Player and am unsure how to get to this using another player, but I'm sure it can be found.
Using my particular player, When the disc starts to spin, press stop. When the main screen for the player pops up with the title number selections, use the chapter skip button to select title number three. There you will find another Phantom Quest episode that is animated in Super Deformed and in the original Japanese. If you use chapter skips during this, you also find a slightly different opening scene, a behind the scenes featurette and the credits for the behind the scenes.
All easter eggs were generously submitted by SirDonk