THE ONE WHO KNOCKS
A number of outposts have memory cards to collect from their safe houses once liberated, which contain drug recipes and other information about the local illicit trade. Memory card 16 found on the south island references a raid on a Meth super-lab in Mexico, giving intel for mass manufacturing the product to "recapture some of the markets lost to the product coming out of New Mexico."
This is no doubt a reference to the high quality Meth being produced by Walter and Jesse in the TV series Breaking Bad.
ON THE NAUGHTY LIST
Down in Willis Huntley's bunker under Badtown you can see what looks like a large boiler tank in the corner of the room. Get close to it and you can read the warning label on the side, which says "Christmas has been cancelled. Apparently, you told Santa you've been nice this year. He has died from laughing."
Guess that means no presents for the island inhabitants come December.
Another amusing warning label can be found on any of the jet ski vehicles, by zooming in on the area just below the handlebars. The label reads "Playing too much Video Game may lead to aggressive behavior. Handle with care. Herp derp."
Something tells us they're not taking this seriously.
BUCK STOPS HERE
While working with Willis Huntley he will phone you at some point and send you after a hit man named Buck, to which Jason replies in a Southern accent "So his name is Buck, and he likes to f..." before the call cuts out.
This is a reference to Buck, the male nurse who abuses The Bride while she is comatose in Quentin Tarantino's Kill Bill Vol. 1.