The other one concerns transports in a city. I attacked this city, and after killing off the infantry I was surprised to see a transport defending the city! However, when I attacked it a Cavalry pops out from under it and defends the town.
I guess this is because the transport has got a higher defence than the Cavalry, but I have never seen anything like this with Battleships or Ironclads in a city. Also, it´s kind of stupid not knowing what you will attack (except that its defence is lower than the transport´s).
Note that the transport only had 1 HP, while the fortified Cavalry under it had 3.