Trivia: When Stan Lee first created the Hulk, he wanted the Hulks' skin to be gray just like classic monster movies. When making the first comic of the Hulk, the gray for the Hulk was either too dark or too bright. Stan Lee then decided to use green for the Hulk's skin color since green was not being used for other Marvel superheroes.
Trivia: Originally, the 2008 Marvel Cinematic Universe film "The Incredible Hulk" was written as a direct sequel to this film, but it was ultimately retooled to be a stand-alone reboot. This explains some interesting connections the two films share, not the least of which being that this film ends with Bruce in hiding in South America, while "The Incredible Hulk" opens with Bruce hiding out in Brazil and being discovered. And interestingly enough, if you ignore the prologue sequence and Iron Man cameo at the end of "The Incredible Hulk", they still actually fit together quite well.