Box Office Bomb: Production costs: $150 million (not counting marketing). Worldwide gross: $263 million. This movie bears the distinction as being the Marvel Cinematic Universe's first and only flop, and even still, the film managed to break even with post-theatrical revenues since it came out right before advertising budgets on movies of this kind exploded. Even still, an underwhelming box office total likely contributed (along with the distribution rights issue with Universal) to the decision to not make another Hulk movie, even after the Marvel Cinematic Universe really took off with The Avengers (2012).
California Doubling: Although the final scenes are set in Manhattan (Harlem to be exact), they were shot in Toronto, with the initial showdown between the Hulk and the Abomination being filmed on Yonge Street. Several Toronto icons are visible, most notably the "spinning disc" sign for Sam the Record Man, and the marquee of the Zanzibar Tavern.
Cast the Expert: The master that teaches Bruce meditation techniques (and presumably some of the moves he uses on the thugs from the factory) is played by Rickson Gracie, a legendary Brazilian Jiu-Jitsu practitioner who also became a yoga adept under pioneer Orlando Cani. Amusingly, he is credited instead as an instructor of Aikido, a martial art Gracie doesn't practice and which has somewhat of a backlash against in the BJJ community.
Contractual Obligation Project: Robert Downey Jr. made a cameo as a favor to Marvel Studios, which he acknowledged as a smart move on Marvel's part, because when he was promoting his film he would also have to mention their other production.
I did a big action movie called The Incredible Hulk. You know what went wrong? It needed a better script... I thought maybe we should try to make one Marvel movie that was at least as good as the worst Chris Nolan movie, but what the hell was I thinking?!
Dawson Casting: General Ross asks Emil Blonsky's age. Ross guesses the age of 45. Blonsky states he is 39. Tim Roth was actually 46 at the time of the movie's release. Justified, as Blonsky is supposed to look older than he is due to the excessive (even for a member of special forces) wear and tear he has put his body through.
In an alternate opening, a depressed Bruce Banner arrives at the Arctic to shoot himself, but transforms into Hulk before he can do so. Animatics show a version where Bruce actually turns the gun on himself and fires, then we see Hulk's POV as he spits out the bullet. This scene is canon, as a version of this scene is referenced in The Avengers (2012). Within this same scene, Captain America can be seen in a slab of ice during the avalanche.
Extended footage of Banner in Brazil exercising, meditating, working at the soda factory and building a centrifuge out of stuff scavenged off the streets of the favela.
General Thaddeus Ross discovers that Banner is attempting to cure himself. Ross and Blonsky inform General Joe Greller of Banner's condition.
An extended version of Ross informing Emil Blonsky of the Super Soldier Serum, mentioning that it can lead to mental instability.
Banner delivers pizza on the Culver University campus. A group of sorority girls refuse to pay him, and he tries to intimidate them by telling them they won't like him when he's angry. They merely call him a pervert.
An extended scene between Banner and Betty Ross after she reunites with him and brings him to her home, where they discuss General Ross and Samuel Sterns.
A dinner scene between Betty, Leonard Samson, and Banner.
Banner and Samson discuss Betty. Samson probes Banner about his mysterious anger problem.
An extended scene between Banner and Betty before the military attacks.
After finding Bruce and Betty in New York City, General Ross tells Kathleen Sparr to interrogate Sterns, after which there is an extended version of Betty talking to Ross.
Samson calls Betty and gives an emotional apology for ratting Banner out to the military. She forgives him but states that she does not want to come home yet.
Directed by Cast Member: In addition to doing rewrites, Edward Norton actually directed himself in some of his own scenes too, such as the campus scenes, to save time when the director was busy working with 2nd-unit.
Executive Meddling: Originally, Marvel Studios wanted Mark Ruffalo to play Bruce Banner in this movie, but Universal had Edward Norton on contract for a handful of movies, and decided to have him play the lead in this one. Marvel ultimately parted ways with him come The Avengers and cast the actor that they wanted from the start.
Fake Nationality: The cast used a few non-Brazilian actors to play Brazilian characters (the factory owner and the leader of the bully trio). Their attempts to speak Portuguese sound ridiculous to real Brazilians.
Inspiration for the Work: Louis Leterrier's primary inspiration was Jeph Loeb and Tim Sale's Hulk Gray (a retelling of the character's first appearance). He replicated every comic book panel that he pinned-up during pre-production, from the many comics he browsed, in the final film.
Missing Trailer Scene: A scene where a despairing Bruce Banner arrives at the Arctic to commit suicide was featured in the trailer, but was deemed too depressing for an opening and too sensitive for young viewers and was removed from the film. It was later included in the deleted scenes on home media and officially canonized in The Avengers.
Role Reprise: While Lou Ferrigno, the actor that played the Hulk on television, doesn't do the motion-capture for the character in this movie, he does lend his voice to the character.
Screwed by the Lawyers: The Hulk has the dubious distinction of being the one hero with his own solo movie that was introduced in Phase One... and not given a sequel in Phase Two and Three. All subsequent appearances of the Hulk or Bruce Banner have been full appearances in the first four Avengers movies and Thor: Ragnarok, and cameos in Iron Man 3, Captain America: Civil War, and Captain Marvel (2019). Part of the reason for this is that Universal still has the distribution rights to the character's solo films so Disney/Marvel Studios can only put him into the Avengers movies.
Star-Derailing Role: This movie was a moderate success, but it was also the last starring role for Edward Norton in a much bigger production, because afterwards he would at best be casted for smaller roles in bigger movies and at worst get bigger roles in smaller movies. He's had incredible success with other, smaller films and seems comfortable with that.
Wag the Director: Edward Norton rewrote the script himself to bring the film closer in line to the comics. In certain posters, he was credited under the pseudonym of 'Edward Harrison'. Norton's writing credit was later denied by the WGA, and Zak Penn is the only writer credited.
According to Louis Leterrier, the final scene (Banner grins as his eyes turn green) was a deliberately ambiguous shot: it was meant to show that Bruce finally learns to controls Hulk (for a sequel) or will become a menace (as the villain for The Avengers (2012)). Neither of which has happened, but Hulk did attack the Helicarrier in The Avengers.
Martin Starr briefly appears as a computer geek that Banner bribes with some pizza. He would later play a teacher nearly a decade later in Spider-Man: Homecoming. Kevin Feige would eventually confirm that both of Starr's roles are the same character.