Task Finder
...
There are secret messages on the Special Edition version of the paper pack-in GTA 5 map. The messages can be seen only with a UV (black) light. [1]
The lengthiest message reads:
T.P.E - Trevor Philips Enterprises. Weaponry, narcotics, intimidation and casual wear. Lago Zan Cudo. Great Ocean, Highway north, through north Chumash, 0.5 miles past Raton Canyon. When guard rail ends, follow the dirt road down the docks. Bring $500,000 cash.
Additional messages can be found on other parts of the map referencing aliens and the Buzzer and Lazer aircraft.
There are even more weird secrets on these images. Check out the full map in the image below, or browse the complete gallery here.