Déjà Vu Easter Eggs

[Maxer 64]

Can you please list all (or almost all) the easter eggs in Déjà Vu - Gryphon Revisited?
If you don't remember some of them, just list the ones you know/remember.

[Legendslayer222]

There is a Déjà Vu walkthrough on this very site and it has an Easter Egg section, here:

http://www.unrealsp.org/community/maptips/dejavu/dejavu-18.html