a different line of reasoning: during the gala, it was nighttime, so the animals were already a bit scared on account of the loud noises and the darkness. this time around the noise was much less, plus it was dusk rather than full-on night.

People, It's obvious that during the Discord Fight, Fluttershy Leveled Up significantly in so many levels her Skill Level Increased to the point where she can now control those high level Animals.