We are indeed carrying our tradition of running jokes in QG5.
There will be a moose(of sorts) and The Black Bird. We don't
have too many references to other Sierra Games, though.

The one easter egg I will mention in QG5 will have something
to do with the dragon's breath ale.

Dancing is popular in this game. Nawar dances at the inn, and that is
an easy one to catch. Much more tricky is to catch Budar dancing at the
inn. If the player plays his game thoroughly, the Hero might get to
dance at the Gnome Inn, or with an absolutely scintilating lady, if he
thinks to join her.

The Science Lab should have a couple of amusing things to find when you
are searching for things to do.

Those are the ones that I can think of right now. There are others, and
will be much more before the game ships.

Thanks,
Lori

I've got currently a sneak preview demo of Quest for Glory V, and I've even found some easter eggs in these. This truly shows that Lori is telling the truth! If you can find some easter eggs in the sneak preview, then you're gonna find many easter eggs in the full game! :)

You can find many inside jokes about waiting till the game is released, and then you'll be able to enter this room, like my personal favorite here. You can't use this ship until the game is er.... shipping.

The mountains you can see at the palace look very much alike the logo from Sierra On-line. When you look at it, you can read that it's indeed the half-dome. It's a subliminal suggestion to buy more games.(I know that these aren't the good mountains, but I've currently managed to get a good picture of it because of the palette)

The moose has also already been spotted! When you look at the preview scenes to the west at the gnome's inn, you'll see the moose(No picture either, you can see the reason above)