I wrote a theory for Gary's return as a floating head. It's somewhere out there in the pages of AVPG history. I remember it caught some folks off guard.
Found it:
"I just figured when Olivia is looking at the predator masks behind glass, the camera will keep panning to the left until you see Gary's head sitting there like one of the masks. That's when jr. will say, "and this is dad". Gary's eyes pop open, and he floats out to meet them on a tiny little hovering space platter. Then he takes her on a tour of the whole place and shows off all the cool predator gadgets while constantly saying "remarkable weaponry".