If you've played Animal Crossing: Wild World, then you'll recognize a reference in Phantom Hourglass. When you first meet the Postman, you and he will talk for a moment. He'll ask you that you try not to shoot him with the slingshot out of the air. This is in reference to Pete the Postman in AC:WW, who suffers a similar fate that the Postman in PH is trying to avoid!