Actually if you think about it, the fight makes sense...
Kagura thought that Erza would be blown away by her sword, but Erza Stopped it(which i think doesn't make sense), Kagura shocked, was caught off guard, Erza sent her flying, the Impact of Kagura hitting the ground probably activated the pillar falling (or minerva did it) and then Kagura got back up, and etc.
Technically Kagura didn't lose to Erza, but to Minerva >.>
The flashback makes sense, Erza didn't know her name or realized it was her,Until she said she was Simon's younger sister and then she realized it was her.
Yeah, the fight could have been better, but I'll accept for what it is.
idk. Thoughts?