With the booming success of Spider-Man (1994) and X-Men (1992) on FOX, UPN wanted a piece of Marvel's animation success, and so a new series was commissioned. Given the popularity of the character, and most of Marvel's heavy hitters were either already on FOX or had been done before, at this point in time, it simply had to be The Incredible Hulk. Marvel wanted The Hulk in his own show too, as there was not one, but two backdoor pilot attempts in both Iron Man (1994) and Fantastic Four (1994).
The show mixed parts of the live action The Incredible Hulk (1978) TV series and the comic books. One notable aspect would be the appearance of the Hulk is not only modeled on the classic comic look but also the live action portrayal by Lou Ferrigno (who also voices the Hulk in this series).
The UPN executive assigned to the show really had no feeling for what the Hulk was about or what was most important to an action-adventure show in general, or to Marvel fans in particular. There were a host of creative differences, but what was discussed in most of those network meetings was her obsession with fashion-she kept insisting that everyone look like they just-stepped out of a shop on Rodeo Drive-hardly a look that would fit any of the main characters. The episodes delivered to network tended to reflect the creative choices of the production company over those of network. Cut to Season 2. The axe falls. The edict came down from network that the show would be pulled from New World unless there were a change of creative personnel who would toe the line; so the second season got a new producer, director and crew.
She-Hulk's cameo appearance as a member of the Avengers in the Fantastic Four (1994) series had to have taken place after her journey to New York in this series because she arrives to New York and meets The Thing for the first time in this series.
In the comics, Dr. Walter Langkowski was trying to unlock the power of the Hulk with gamma rays. However, the gamma rays did not directly mutate his cells; rather, the gamma energy breached an inter-dimensional barrier, and allowed Langkowski to channel a mystical being called Sasquatch (which explains why he's the only gamma-irradiated being who isn't green). Of course, Langkowski thought that it was due to the gamma for a long time (episode 1.06 "Man to Man, Beast to Beast").
The Gray Hulk has a different design in episode 2.01 "A Hulk of a Different Color" than he had in the flashback in episode 1.01 "The Return of the Beast Part 1" and at the end of episode 1.13 "Darkness and Light Part 3".
Gray Hulk was set up at the end of the first season to play a prominent role in the second season. Although he does appear twice in Season 1, the Season 2 premiere is the first to actually voice debut of the Gray Hulk.
In another example of inter-series continuity, the Hulk's reference to the Thing as his enemy, and the Thing recognizing Rick Jones carry over from Hulk's earlier appearance in the Fantastic Four (1994) episode 2.09 "Nightmare in Green" (episode 1.08 "Fantastic Fortitude").
In the comics (She-Hulk (v1) #1), Jennifer Walters was injured by a criminal angry about her legal work, rather than by Dr. Doom's robots. Otherwise, her origin was the same - her cousin Bruce had come to see her, she was injured, and out of desperation, he gave her a transfusion of his own gamma-enriched blood (episode 1.07 "Doomed").
In the comics, the curse of the Wendigo resulted from cannibalism, rather than ego. This was probably too much for children's TV. The Wendigo was also in Canada, but Hulk had just fought a furry beast in Canada in episode 1.06 "Man To Man, Beast To Beast", so the location was changed (episode 1.10 "And the Wind Cries&... Wendigo!").
In the flashback to when the Hulk was created, he turns gray before green. This is a homage to Marvel Comics' Incredible Hulk v1 #1, the first issue to have a Gray Hulk . (episode 1.01 "The Return of the Beast Part 1")