riding in cars with babies

We went up to Brooms Head with some friends over the long weekend. It's a pretty little place with (wait for it) sweeping views, about five hours north of here. As usual, as we were driving along I pointed out all kinds of stuff to the baby: cows, trucks, cranes, Big Bananas; you name it, I named it.
So I felt pretty silly when, just as we were nearly home again, I happened to bend down to exactly his eye level and realised that the only thing he can ever see is the tops of trees and the sky. Oh.
He's a good sport though; plays along, looks out in the direction of whatever I am pointing at and appears to go, "Oh, yeah...so it is."
He probably thinks his mother is quite mad, seeing a whole bunch of invisible stuff floating by. Or maybe he sees it too, in his mind's eye? I hope so.