Shown in the opening credits are the blueprints for the weapons we later see deployed against The Hulk which were created by Tony Stark.
The credits are filled with Easter eggs including a brief reference to Samuel L. Jackson's Nick Fury.
Later seen in the film played by Ty Burrell, Doc Samson is another character in the Marvel universe who was capable of fighting The Hulk.
A friend of Bruce Banner's in the comic books, Rick Jones is one of the reasons that Banner originally was struck by the gamma bomb that turned him into The Hulk. Jones also turned into a super-strong hero himself, A-Bomb.
Stan Lee's cameo in the film is as a man that drinks the tainted soda bottle. We'll never know what happened to him either.
The theme from the classic Incredible Hulk TV series, titled "The Lonely Man," plays during this section of the film.
Stanley's. Stan Lee's. Stan Lee. He co-created The Hulk you know?
The man who plays the owner of Stanley's is Paul Soles, who previously provided the voice for The Hulk in the 1966 animated series The Marvel Superheroes.
Lou Ferrigno previously portrayed The Hulk in the 1970s.
General Ross is a noted fan of Captain America and even has a picture of him hanging in his office.
The container that includes the chemicals for the Super Soldier Serum includes the name of Dr. Reinstein, the alias of Abraham Erskine from Captain America: The First Avenger.
This is of course in reference to The Hulk's trademark purple pants.
The two characters interviewed on the news report about The Hulk's attack have a history with the character. Jack McGee was a character from the original TV series, while Jim Wilson was first in the comics, befriending the green giant.
Blonsky's transformation into a monster is noted as potentially being "an abomination" by Dr. Sterns, which is fitting since The Abomination was the character's name in the comic books.
This fourth wall breaking tease hints at a villainous future for Sterns who was the giant-headed villain The Leader in the source material.
The package to Bruce from Betty is addresed to David B., a reference to The Hulk's name change in the TV series where he was called David instead of Bruce.
Robert Downey Jr. returns as Tony Stark, for some reason speaking to General Ross about recruiting The Hulk for The Avengers.