Detective GAF we really need to solve the Mt Chiliad Mystery. There is spaceships, Dinosaur eggs, jetpacks etc. We need to find out what the hell is going on ....i'm sure it has something to do with the Epsilon cult.
39 pictures of Blueprint map under blacklight.
I don't know whether you'd call it an "easter egg" or it's just a cool little callout, but Lester (?) talks about some of the more popular criminals around the city and how a couple of years ago some Eastern European guy was looking to make it big, then disappeared completely.