Like... why build (or grow, I guess) a tower for your spaceship to sit on? Why have a throne for the tree guy to sit in? Why does the girl not know the word "astronomy"? Why is the boy so completely blahze about a giant alien chasing him and putting a crown on his head? Why did he even go to the tower when the orb growing was enough to scare him away? Why did the crown painfully burn the Doctor to the touch? Why did the Doctor just tune out and watch all the Christmas lights when there's a ten-year old kid ostensibly being attacked by some unknown threat behind the nearby door? Why did the family even go to that house? Why didn't the aliens just grow a... tree to serve as a vessel for their species? Why not try contacting the humans harvesting the planet?
And further, what happened to the one British airman who was supposedly seriously wounded? It's funny how they cut from the family reunion to them all sitting around inside the house. I guess his not-wounded wingman just went for a walk.
