Billy Crudup and Edward Norton were initially approached for the role of Bruce Banner before Eric Bana was cast. Norton turned down the offer due to his dislike of the script. Norton would eventually portray the titular character in The Incredible Hulk (2008).
In an early script version, Talbot becomes the Abomination and fights the Hulk at the movie's end.
In the script's first two versions, David was called Brian, like in the comics.
The animation studio originally made Hulk a darker shade of green, similar to how he was later depicted in the Marvel Cinematic Universe. Ang Lee wanted Hulk to resemble his comic counterpart better, resulting in the brighter green skin shown in the final film.
The order of the scenes leading to the dog fight causes a continuity issue: David sends the mutant hellhounds after Betty, then Betty arrives at her cabin, and David calls Bruce. After transforming, Bruce finds Betty without prior knowledge of her whereabouts and somehow finds her before the dogs do. The novel rearranges the scenes correctly: Betty arrives at her cabin first; after David calls Bruce, Bruce's scuffle with Talbot and his second transformation happen simultaneously with David unleashing the dogs. Then the Hulk sniffs the air, and his heightened senses "pull Betty's scent" from it to find her, like in the illustrated screenplay. Additional materials instead have the Hulk use Bruce's memory of the cabin to guess Betty might be there as her father's men would surround her house.
An earlier screenplay had slightly more physical interaction between Betty and the Hulk during their two scenes.
The illustrated screenplay describes the build-up to the Hulk-dogs' arrival like something in a horror movie: a series of smash cuts between their POV of barrelling through the woods and Hulk protectively holding Betty in tense anticipation.
As storyboarded and shown in concept art, the dog fight would've had the Hulk naked throughout the scene. To keep a PG-13 rating, they tried to find ways to cover his modesty with the trees and branches, but Ang Lee thought it was reaching Austin Powers-levels of silliness.
The dog fight would've been more violent, with the Hulk killing the hounds more gruesomely, like crushing one's head in his hands. Betty would've also gotten minor injuries from the fight.
Concept art shows the Hulk-dogs as slightly larger than in the film.
James Schamus began work on the script for the sequel before the release of Hulk, and early drafts featured the Grey Hulk. Schamus also considered the Leader and the Abomination (still Talbot) the main villains. The Leader eventually became the Big Bad of the video game sequel.
Talbot suffered a grislier death, getting himself riddled with bullets after shooting at the Hulk.
John Turman script (1994)
Bruce suffers from an ulcer, which he's had since high school. It's healed after he gains his powers.
Betty is an FBI Special Agent working in counter-intelligence.
Rick Jones appears and gets narrowly saved by Bruce at the bomb testing site. Marlo Chandler appears when the pair travel to Vegas and need somewhere to stay.
The accident plays out much more like the comic book version, with someone (Edward Leder instead of Emil Blonsky) sabotaging a gamma bomb, leading to Banner getting gamma-irradiated. Leder also gets exposed to radiation, eventually turning into the Leader.
Bruce can unwittingly disrupt electronics and cause lights to burst when angry, at one point causing a giant neon sign to explode above him.
The story ends with Bruce turning into the Hulk one last time after disarming an improved gamma bomb made by Leder, with the implication that the change is permanent. Betty pleads with him to remember, but the Hulk shakes his head and walks away, with Rick following him.
Michael France script (2000)
Bruce and Betty receive an Age Lift; they're in their 20s instead of 30s.
Betty's surname is Garrett instead of Ross, and she works in a hospital.
This version of Talbot is friends with Bruce instead of a rival for Betty's love. He genuinely wants to help Bruce cure himself, even objecting to Ross’ orders to form a strike team to go after the Hulk. In the end, he even buys Bruce time to escape.
Samuel Sterns becomes the main antagonist, The Leader. He experiments on and mind-controls Carl Creel, turning him into the Absorbing Man, the secondary villain.
Bruce can cause electronic devices to short out when he's close to Hulking out, like in the Truman script.
The gammasphere is a 50ft model of an atom surrounded by 24 rings of piping suspended from the ceiling by chains, with an eight-foot glass orb full of liquid as the core, which Bruce calls a new liquid computer.
Bruce, project leader Sterns, and a grad student lab assistant named Curtis demonstrate the gammasphere's capabilities to politicians and military representatives to secure more funding. Unknown to them, one of the senators made a deal with Creel, who attended the demo as an anonymous observer, to move parts of the gammasphere to a U.S. weapons lab.
Like the film, the accident happens while someone tries fixing a problem with the gammasphere, except this script version is more extended and elaborate. The gammasphere almost overloads during the demo before Sterns tells Bruce to shut it down. They enter the gammasphere on harnesses the next day to check the gas piping. Creel tampers with the security cameras, sneaking into the gammasphere control room and copying data before starting the gammasphere. Bruce tries to help Sterns while Creel attacks a guard who catches him; Talbot hears this over a walkie-talkie, making him rush back into the base. The gammasphere's ceiling supports weaken, making it sway. Sterns falls and gets his head submerged in the liquid computer core, and Bruce falls past the green isotope slab and into the gamma charge cage moments before gamma rays blast him. After he and Talbot enter the room, a gamma blast hits Curtis as he goes to help Sterns. Gamma rays ignite and pour through the computer core fluid, surging through Sterns' eyes and mouth. The gamma blast on Bruce ends, but the isotope slab's broken half falls toward the plexiglass cage without obliterating it. The laser array in the gammasphere goes wild, firing blasts erratically; one cuts a metal girder that falls onto Talbot, knocking him out cold. Curtis leads Sterns out of the room, noticing the gammasphere is about to fall. As Bruce plans to escape the cage, he sees the unconscious Talbot in the path of the laser strikes, and a flash of green appears in Bruce's eyes. The slab knocks out the cage wall without killing Bruce; Talbot awakens to see laser blasts approaching him, but he can't move. Bruce saves him, and they dive out of the blast door before the gammasphere falls. The four men all escape to safety on the upper levels.
After the gammasphere accident, Bruce goes to Curtis’ apartment to check on him, only to find that Curtis now resembles a "gamma leper" with green boils on his skin. Curtis seems unaware of how bad he looks, playing off his sickness as some cold. Sometime later, while Bruce drives Curtis to the hospital where Betty works, Curtis sees his reflection in the rear-view mirror and freaks out. Half of his body starts hulking out; the script describes him as resembling a mix of Jack Kirby Hulk and one Picasso might've designed. He starts screaming at Bruce, claiming that Bruce killed him... and then his skin melts off, and his body turns inside out!
One of Bruce's nightmares has him trapped inside the Hulk, with his outlined face pressing against the Hulk's chest, struggling to get out, screaming for help, and suffocating.
Sterns blasts concentrated gamma energy at the Hulk with a futuristic bazooka-like weapon, gradually weakening the Hulk. His musculature appears to melt off his body until he looks 200 years old.
In his transformation's final stage, Sterns's body looks frail, neural activity makes crackling flashes of energy visible within his skull, and his voice now sounds computerized. And that’s before he uses a transformation chamber to mutate even further, gaining a body as powerful as the Hulk’s to match his enlarged cranium.
Forced to confront the mutated Creel without access to the Hulk transformation, Bruce spills 24 chemical jars onto him. Creel’s body reacts to them as they mix, with each section mutating differently. A moment later, Creel reappears scarred from the acid, and parts of his body still react uncontrollably to the chemicals. Noticing an odor, Bruce realizes the chemical reactions within Creel are turning him into nitroglycerin. After Bruce baits Creel into striking a wall behind him and dodges at the last second, the chemical reaction inside Creel reaches its flashpoint; he explodes into a massive fireball that blasts through the wall Bruce previously tried to penetrate, leaving nothing of Creel behind.
Bruce resolves to become the Hulk again, jumps into Sterns's gamma turbine, and burns alive within the gamma energy vortex.
A further enhanced Sterns uses his telekinetic ability to close the Hulk's windpipe and cut off his air supply as they fight.
Sterns meets his end getting sucked into a gravitational vortex in the sky caused by the gammasphere's anti-matter drive breaking down. His body disintegrates, and atoms stretch apart.
Foreshadowing: During an early conversation with Bruce, Curtis offhandedly foreshadows Sterns's transformation into the Leader, saying that Sterns's head would explode if it gets any bigger.
There are numerous nods to the comics:
Bruce's full name is given as Robert Bruce Banner.
Talbot is a Major serving under General Ross.
Bruce saves someone's life during the accident where he gets blasted with gamma rays; in this case, he saves Talbot from getting crushed.
A news report mentions "Tales to Astonish!", a comic series where the Hulk appeared.
At one point, Bruce partially transforms while still exhausted from a previous change, resulting in the Grey Hulk form.
Edith's death was due to a medical condition worsened by David's abuse, compelling Bruce to pursue medical research independently of his scientific projects. David experimenting on himself or Bruce never gets mentioned.
Bruce admits to Betty that the reason he tries to suppress his anger is because he inherited his abusive father's temper, and is afraid of ending up like him.
Bruce and Betty have a much more hopeful ending. Bruce is still a fugitive Walking the Earth in search of a cure, but he has Betty's support, and she moves into his apartment to conduct her research.
