Everything about the Center. From the way it enters minds and drives people insane, to the hideous mutant abominations it uses as foot soldiers, to its apocalyptic true form.
There is one moment in the movie perfectly showcasing how twisted those foot soldiers are. Superman KO's a giant, yet seemingly normal pterodactyl with relative ease. In the middle of the final battle, the unconscious pterodactyl's body starts bulging unnaturally, before several other dinosaurs burst out as if the pterodactyl was just a flesh piñata.
Hal Jordan killing a North Korean Soldier by accident due to a misunderstanding with blood and brain matter splattered on his face. Poor Hal gets PTSD from the event and gets labeled a coward and Communist sympathizer simply for not wanting to kill more people.
Wonder Woman is considerably Darker and Edgier in the film considering she liberates a group of enslaved women and rape victims who then proceed to take the weapons of their oppressors and slaughtered them all with bodies left behind. She's seen partying with the women and she acts as if nothing is wrong while bodies are littered outside her shack much to Superman's horror.
On a lesser note, Superman was pretty scary when he showed up to admonish Wonder Woman considering his eyes are glowing red when he bursts through the door.
