Mikey's reaction to being called a monster is downright heartbreaking. Seeing the usually upbeat and goofy teenager inches from tears is one of the most painful things in the movie.
Mikey: It wasn't just fear in their eyes. It was actual hate.
April and Casey jumping between the turtles and the police to give them a chance to escape, knowing it would result in their arrest.
The brothers' fight on the ride home after having their asses handed to them by Bebop and Rocksteady. Like real siblings, they know exactly what to say to make it hurt the most. Leo's Wham Line is what hurts the most that no one says anything afterwards.
Raphael: You think standing on the sidelines makes you some kind of hero?
Michelangelo: You can't just push past me like that, bro!
Raphael: You were being a nitwit! You were gonna lose that thing!
Michelangelo: I wasn't going to lose it! I had it!
Donatello: I had it right in my hand and you acted like I wasn't even there!
Leonardo: It is not my job to make your presence known, alright? Get out your head and communicate!
Raphael: Well, what'd you expect!? He's all logic, no skill!
Michelangelo: Oh, coming from the guy who's all instinct, no restraint!
Leonardo: What do you know about anything!? You're all heart, no brains!
Donatello: How could you!? You may know a lot about strategy, but you know nothing about feelings!
