The scene that annoyed me the most is how the heck Rey knows about Jedi Mind Trick all of a sudden when 30 min ago in the movie she was thinking Jedi's were a myth. And now she knows Jedi mind trick? Made no sense to me.
IMO it was the scene when Ren tried to enter her mind. I think it "awoken" something inside of her especially when she "fought" back against him in that scene. I'll be the first to admit it's a bit convenient but I have some theories.