Dex-Starr of the Red Lantern Corps, known to some as Ruffles the Rage-Cat. Also called Pukecat in some circles, due to the... acid-blood-puking nature of the Red Lantern power signature.
Also, Hal (as Parallax) is called "Halallax", and Kyle (as Parallax) is called "Kylellax" by some fans.
Follow the Leader: Alan Scott began his series as an engineer, but by his third story he's going after a job in radio at Apex Broadcasting. Add feisty female reporter Irene Miller to the cast, note that Alan took the job so he can keep up with news and learn about crime more quickly, and suddenly it becomes very apparent that Green Lantern is copying the same formula as Superman in an attempt to be just as successful. Even Green Lantern's original powers involve the ring allowing him to fly and making him invulnerable to metals, much like Superman. Constructs made of energy are the exception, not the rule.
Science Marches On: Some color theorists have suggested cyan should be considered a color of the rainbow (specifically, it's between green and blue) whether they will ever make a Cyan Lantern Corps (and what emotion it will represent) is unknown.
Ron Marz stated that he was in the process of bringing the Corps back near the end of his run, which would have seen the Corps rebooted into a smaller group led by John Stewart and Ganthet as the Guardians. Unfortunately his contract ran out, Judd Winick went another way and we had to wait till Rebirth to get a corps back.
Also by Marz was the Elseworlds Green Lantern: Camelot in which The ENTIRE cast of Green Lantern would have been transposed to the time of Camelot, with Alan Scott as King Arthur, Hal Jordan as Lancelot, and Ganthet as the Lady in the Lake (Marz: He has a dress!).
After losing his yellow Power Ring and after the Zero Hour crossover, then-current writer Beau Smith wanted to revamp Guy Gardner as an Indiana Jones-type hero (i.e. without his powers), but he was forced by editorial to add the Vuldarian shape-shifting powers. You can learn more here.
During the planning stages of Infinity, Inc., Jerry Ordway thought about including a teenage male Harlequin who was to be mainstream comics' first openly gay character. Because the team already had two GL-related characters (Jade and Obsidian), though, the idea was scrapped.
Larry Niven wrote "The Green Lantern Bible", which would have established the Post-Crisis history of the Green Lantern Corps. Some of the stuff would later appear in the 1992 one-shot "Ganthet's Tale" (co-written and drawn by John Byrne), and parts of the bible can be seen in his 1991 book, "Playgrounds of the Mind".
Green Lantern: Rebirth's original script was slightly different, most notably in having Batman be host to Parallax (which Executive Meddling overruled), but also stating that Sinestro would be an anarchist. This element was apparently abandoned internally, as Johns wrote Sinestro as a fascist going forward.
Johns' early issues of Green Lantern had Black Hand and Shark as characters revamped in-universe by Evil Star, an old Green Lantern enemy. A few issues later, a Blue Lantern mentions Evil Star menacing her homeworld. This storyline would be abandoned due to Blackest Night.
Box Office Bomb: Despite having a strong opening weekend, the box office gross ultimately tanked. Budget, $225 million (plus another $100 million for marketing, creating a $325 million threshold just to meet the budget and a likely $650 million target to break even). Box office, $219,851,172.
Ryan Reynolds indicates that he does not consider making the film a positive experience despite meeting his future wife on the set. In 2016, his Wade Wilson was strangely adamant that his costume not be green or animated, and Deadpool 2 featured Deadpool killing the past version of Ryan Reynolds who approved of the script for Green Lantern.
Meanwhile, Martin Campbell heavily criticized the studio for hacking the film to pieces during the editing process, which he claims resulted in the omission or alteration of numerous elements which would have made for a stronger film.
Creator Killer: Director Martin Campbell's career took a heavy blowback with this film and he did not helm another project until 2017's The Foreigner.
This film was going to launch the DC Extended Universe until its horrible reception from fans. This certainly helps explain its only containing the barest hints of foreshadowing for Sinestro, as well as Amanda Waller showing up despite having no impact on the story.
Superman made a cameo in an early script. Writer, Marc Guggenheim hoped Tom Welling would do it, implying the movie would be set in the same universe as Smallville.
Executive Meddling: Allegedly, but if you have seen the movie it does seem like many scenes were trimmed or cut, and it is known that some scenes were re-shot after production wrapped up. There is an extended version that adds a few minutes, but still leaves out a lot according to at least one source.
One thing I feel needs mentioning: this is not Martin Campbells cut of the film, but the studios. I live in New Orleans where it was shot, I read the shooting script, all of which was painstakingly filmed with intense research, and all of that was left on the cutting room floor a sort of combination of what happened to Daredevil and Watchmen, respectively character development sacrificed for CG, scenes made irrelevant by removing their setup. The movie in the theater starts with an explanation of mythos that is made redundant by the more natural, scripted questions from Hal when he gets the ring. Ten minutes of childhood Hal, Carol, and Hector that sets up Hals first ring construct is reduced to an awkwardly placed flashback in the middle of another scene. The training with the ring is almost completely excised except for one minor scene. Most appallingly, the ending completely deletes the fact that Kilowog, Sinestro, and Toma-Re arrive at the end and help Hal defeat Parallax. Not to mention Parallax was supposed to be a 3rd act reveal after we spend the film worried about Hammond going evil, not the main villain for the entire film. I sincerely hope we get a directors cut or at least all the deleted scenes on the video release.
Hostility on the Set: Ryan Reynolds and Martin Campbell clashed repeatedly on set. Campbell has stated in interviews that his first and only choice for the lead was Bradley Cooper. However, the studio was not willing to make an offer to him and ultimately cast Reynolds behind Campbell's back. This lead to an uncomfortable experience on set for Reynolds whose performance was constantly critiqued by Campbell who made him do many takes. Reynolds has stated in an interview with Variety that the film's failure was a huge relief as he had such an unpleasant experience and "dreaded doing it again."
Apart from meeting Blake Lively, the pair of Take Thats Reynolds sent in this movie's direction from Deadpool (2016), which he co-produced, make it clear he does not look favorably on Green Lantern. The Stinger of Deadpool 2 takes it a step further by having Deadpool go back in time to murder Ryan Reynolds before he can accept the role of Hal Jordan.
Over time even Warner Brothers themselves would come to mock the movie. Teen Titans Go! To the Moviesfeatures a group of famous superheroes happily sharing their movie successes. However a John Stewart Green Lantern excitedly mentions that his franchise once had a movie, before pausing and awkwardly mentioning "But we don't talk about that anymore". (Warner Brothers to their credit even put this line quite prominently in the trailer, demonstrating that even they agree with the public rejection of the GL movie).
Averted with Mark Strong. Despite the film's failure, he has said he enjoyed the experience and would be open to playing Sinestro again in the DC Extended Universe. Strong's loyalty would be eventually rewarded by a villain role in Shazam as Doctor Sivana.
Stillborn Franchise: Sequels were greenlit before the movie came out, with the intention of starting the DC Extended Universe with this film. Suffice to say, they didn't go anywhere when the film bombed and dealt a serious setback to those plans, and the Green Lantern wouldn't star in his own movie again until 2020, with the DCEU not starting for another 5 years, well after Marvel fully took hold of the market (said universe doesn't include the Dark Knight trilogy; it was rebooted a third time for the DCEU).
Throw It In!: Carol's line "I've seen you naked! You think I wouldn't recognize you because you covered your cheekbones?!" was an ad-lib.
Troubled Production: After years in Development Hell, the film was jump-started once Warner Bros. (sister company to DC Comics) saw Marvel create their own movie studio with an ambitious plan and a succesful first step, and decided to also start their own Shared Universe of DC adaptations with a "lesser" character akin to Iron Man. The first signs were positive, with a script by Greg Berlanti (who went on to helm the Arrowverse on television) and comic book writers Michael Green and Marc Guggenheim; comics fan Ryan Reynolds as Hal Jordan; and director Martin Campbell, who helmed two successful James Bond revivals. But then Executive Meddling and trying at all costs to have the movie by 2011 (when Marvel would release Thor and Captain America: The First Avenger, and one year before the heroes team-up in The Avengers) started to bring things down. The studio felt the script was too complicated and ordered rewrites, that made the shooting schedule even more tight. Casting continued into shooting, and while filming, Reynolds suffered a shoulder injury which added further delays. Then during post-production the studio basically froze Campbell out of the editing process, cutting large chunks of the movie in detriment of the narrative, and the special effects teams had to work overtime, ballooning the budget even further. Green Lantern ultimately came out to scathing reviews and public apathy, struggling to pass $100 million dollars domestically and barely covering the $200 million budget worldwide. The plans for it to eventually lead into a Justice League were ditched, and instead WB decided to start the DC Extended Universe with the tried-and-true Superman in 2013's Man of Steel.
An early draft of the script contained a cameo by Alan Scott, who was going to be the United States President, and near the end would reveal his own past as a Green Lantern to Jordan, and give him his blessing. He was later revised to become an agent of the Checkmate agency (the Checkmate membership stayed true to the comics), who would approach and offer Jordan membership. Later drafts finally wrote him out of the film, and replaced him with Amanda Waller. Scott would have been played by Pierce Brosnan.
An early script planned a cameo from Guy Gardner, as a football player whom Abin Sur's ring briefly considers before moving on to Hal Jordan, before it was written out.
At one point Superman was in the script (he had a cameo as one of the candidates considered to receive a power ring), but he was cut out because the filmmakers didn't want to depend on another superhero for a success.
Originally they were going to use the villain Legion, until they changed it to Parallax.
They originally intended to make a practical Green Lantern costume to be enhanced with CG but the more they experimented with the technology they knew they needed to make it fully CG, as they didn't want to show audiences another rubber/spandex/leather superhero costume. However, there is concept art for a more Batman-style armored GL look.
There were a few attempts to bring the Green Lantern to the silver screen before this one, the most infamous one being the script written by Robert Smigel in 2004 that would've reinterpreted the premise as a raunchy adult comedy. Very loosely based on the Emerald Dawn storylines, it would've starred Jack Black as a loser furniture store employee named Jud Plato who was selected to become the next Green Lantern on the basis that he "fearlessly" ate severed animals heads for a TV reality show. Reportedly, negative fan reception to this treatment after details of it leaked onto the internet caused Warner Bros. to can the project very quickly.