("spoilers" for the Rainbow 6 mission)
While investigating the apartment you can peek into a wardrobe where you see several black suits with white dress shirts and red ties. Nomad says something like, "Huh, look familiar? Someone could make a killing in this getup."
This seems like a pretty clear-cut Hitman reference, but it seems really out of place in the Rainbow mission -- unless it's a nod to possible future crossover content? Maybe a visit from Agent 47 to one of the swanky places in, say, PN Agua Verde? The golf course, perhaps? Or maybe one of those legal coca farms (you know, *inhales*, for the altitude)?