Ghost Recon Wildlands’ new update features a crossover mission with Rainbow Six Siege showing a little inter-agency cooperation between the ghosts and rainbows. During a casual conversation, two of the characters start talking about that mission that “went south” for the rainbows. The mission? The canceled Rainbow 6 Patriots game.
Source: N4G PC Canceled Rainbow 6 Patriots Game Easter Egg Pops Up In Ghost Recon Wildlands Mission Conversation