Pertaining to the last episode of season 6:
If they flew along with Daenerys' fleet, then how were they able to fly for so long without eating or resting (since there is nowhere to rest and the only thing to eat would have maybe been a few fish)? Even if they stopped somewhere later on the journey, they couldn't stop anywhere going around Old Valyria, which is quite a distance to fly, especially if you consume as much energy as a dragon does.
Does this mean that the dragons took a different route, maybe one over land? But then how did they know where to go and stuff? How did the know what speed to fly at to meet them where they did. Their route is much shorter and dragons fly faster than ships sail, so how did this all work?