Part of the closing credits takes place in a montage of seven quasars, each quasar a specific color of the rainbow. This is based on the emotional electromagnetic spectrum, a Green Lantern theorem that states each color is based on a specific emotion.
SPOILER: There is a scene in the closing credits: Sinestro draws the yellow power ring to him and puts it on. His uniform then glows yellow with the power of Parallax... and like Hammond, so does his eyes.
The opening title is an energy construct formed from many Green Lantern rings.
The DC Comics logo is shaded green, and contains two comic-book images: a shot of the Green Lantern Jordan, and his equipment (power ring and power battery).
The Warner Bros logo shines with green light.
The closing credits are all colored green.