The opening chapter in which the heroes fail to prevent a nuclear holocaust, and the scene in which Clayface and Scarecrow break into Green Arrow and Black Canary's apartment.
Brainiac's brain surgery on Aquaman.
After defeating mind-controlled Batman and Alfred, Superman explains to a confused Captain Marvel that they were infected by microscopic worms. Then Supes looks at his own hand:
Superman: Good Lord! They're in me, too...
Wonder Woman's slowly, horrifically deteriorating condition after Cheetah's attack. At first it manifests as ugly, glowing scars, but when confronting Cheetah again in the Cities, all of Diana's skin is charred, with only a few burnt strands of hair clinging to her scalp.