Seeing Nightmare Moon again was one of the most awesome parts of the entire episode. But my only grief is that the time between Luna first becoming Nightmare Moon and Celestia banishing her sister to the moon was far too short. This could have been a whole episode with Luna telling and showing Twilight how she turned to evil and the responsibility Twilight has, not to let this happen to her.
This was made using traces from MLP FIM
Credit goes to