The Green Lantern in this movie is a composite of three of the ring bearers, the classic Hal Jordan, modern Kyle Rayner and '80s-era Guy Gardner. Hal makes up the character's basic appearance, sans mask; Kyle makes up the mask, badge and wrist gauntlet; while the name and vest come from Guy.
Next to the phone in Green Lantern/Atom's apartment, there's a perfectly framed picture of an Air Force jet, similar to a comic panel. The Green Lantern Hal Jordan was a test pilot fresh from the Air Force.
Lewis Teague was brought in at the eleventh hour to try to salvage the project but was unable to do much with it. Teague asked not to receive credit for his work.
(at around 1h 13 mins) While in the comic it is well known that J'onn J'onzz is from Mars, it is never stated in the film. Thus his "300 degree, beach day" line may be accurate.