It is quite awkward that Carla kept remembering information about Edolas which was a place that she never been before. If I would have been Natsu and them I wouldn’t have been so trusting of Carla. To me that would have been very weird. It was like she knew the specifics of the layout of the tunnels underneath the city. I would have been questioning that right away.
The second anomaly was that Erza Knightwalker knew they were coming through the tunnels. Then again they were making a lot of noise going through the tunnels. They were destroying walls and what not. So that does not really surprise me in the least. Then Knightwalker tries to play it off as if Carla and Happy were suppose to lead them there. You can see that Carla has been put into a weird position.
The King of Edolas Faust is an arrogant asshole, but I guess that comes with being the dictator of an entire world. He purposefully destroys part of the lacrima in order to prove that he will get more. To me that is very wasteful of magic energy in world where it is limited.