I still say the drone wasn't Pat, he's dead, I reckon maybe the "Bunker People" (what's left of the government), Pat was so afraid of, or maybe someone else, removed the body and the boat.

Did no-one else notice that the drone may not be from Pat? They said they saw the lights nothing about a drone. I have had a baker's dozen of wine so I may have missed that. (sorry if someone's already mentioned it, I haven't read all the comments).