Hightower being let go from the academy when a riot was about to happen. Pure luck?
Whether it was by luck or a wild coinicidence that when Hightower was let go/kicked out of the academy over the minor argument fight with Hooks and that one cop in training, that a riot was just starting to happen.
With Hightower intimidating height and the clothes he wore he blended right in to infitrate the mob.
What do you think about that moment in the movie?