The roman numeral on the book shows III - 3. The die on the ground shows 1, 2 and 3, with the 1 facing up. I think the III may indicate a 3 day heist, while the 1 facing up on the die tells us to look on day 1?

I have a strong feelng that the picture I linked represents Rats Day 1. When you first enter the lab, the lab technicians are executed. In the picture there is a chart of alchemical symbols on the wal. From top to bottom from what I can tell: The lone symbol on top is the symbol for Salt.
Right below that is a depiction of Mercury being appoximately equal to Sol (sun, maybe meaning heat?) Below that we have the Zodiac sign for Libra(sublimation) right next to the alchemical sign for Mercury - I haven't been able to find what the image to the right of Mercury is. Below that we have what looks like 3 lines crossing eachother, similar to the union jack - this image MIGHT mean copper. The very last picture on the bottom right - the Philosopher's Stone. I'm pretty sure most of these chemicals can be acquired through day one of Rats, but I have no idea what to do from there.

http://i.imgur.com/LrgxAtp.jpg
Speaking of bullet holes in a skull's forehead

418 is also code for "missing person" quite a few of the gang members in game have this tattoo. Possibly nothing, possibly relevent

Hazode could yo utry to replicate and record this? I'd love to se it!

In the office of Nightclub - Obviously everyone's noticed the paintings. What no one else has mentioned yet is that maybe these paintings are telling us HOW to get into the room that's possibly behind the two bookshelves. The painting above the safe is looking TOWARDS the painting of Rasputin. Rasputin is looking across the room towards another painting with something that resembles a disc on it. RIGHT BELOW THE OFFICE is the DJ area. Perhaps the paintings are actually indications like those for Overdrill. Where people need to be standing, where they need to be looking etc. Bain tells wolf to stay off the dance floor. Maybe everyone else needs to be in these positions while wolf is on the floor by himself? I don't know... needs testing.

berchrker, around monday or so they'll be releasing a live version of the map for everyone to see

yo back to that whiteboard..... are those alchemical synbols like the ones in the guide of bain?

Has the possibility that the rug could indicate Braille been explored yet? Is anyone good with braille that might be able to do something with this?

I might be completely wrong about this, but Overpass Escape is the one that happens between Days 1 and 2, correct? Do you still have to protect/move the meth on this escape? If so has anyone tried throwing bags through the hole?