In the episode "Follow the Leader" there are a lot of mistakes.
1. Amy said "let's make me leader" then Rei replied "No way, I was a sailor scout before you" but this isn't true Amy was a scout before Rei!
2. Rei said "Remember Sailor Moon when we fought the four sisters of Nemesis" and they started playing clips. Later Rei said "Stop stalling Meatball Head and let's talk about who's going to be the new leader" but Rei is the one who brought it up.