If it wasn’t for the return and subsequent recurring appearances of William Hurt’s Thaddeus Ross, then you could remove The Incredible Hulk from the Marvel Cinematic Universe entirely and it wouldn’t change a single thing. Even though the movie hit theaters just six weeks after Iron Man had kicked off the franchise, so-so reviews and middling box office numbers meant it didn’t deliver the hit everyone was expecting.
In fact, it would seem that as of late, the MCU would rather pretend that it never existed given how none of the events seen in Louis Leterrier’s blockbuster have influenced proceedings in the slightest. True, it did feature a shoehorned-in Tony Stark cameo during the credits to continue teasing that a much bigger universe was in the process of being unveiled, but for the most part, the movie remains the most inconsequential installment that the MCU will likely ever see. However, that being said, The Incredible Hulk did feature a very fleeting reference to Wolverine, even though the character was firmly in the possession of Fox at the time.
As well as explaining that the Hulk and Abomination are the results of failed attempts to replicate the Super Soldier formula that created Captain America, the name Dr. Reinstein can be glimpsed on the canister containing the serum. In the comic books, Reinstein was an alias of Dr. Abraham Erskine, who was pivotal in Steve Rogers’ transformation from skinny kid to star-spangled superhero.
The same shot, however, also reveals that the project is named ‘Weapon Plus,’ and in Marvel comics, the clandestine program is directly tied to the origins of Wolverine, with the tenth iteration designated Weapon X.
As ScreenRant explains:
When Thunderbolt Ross’s (William Hurt) motivations to capture the Hulk meet Emil Blonsky’s (Tim Roth) hunger for power, the ambitious general provides the soldier with a modified version of the Super Serum formula. A brief look at the canister reveals the details of its fabrication, which include Stark Industries as the producer and Dr. Reinstein as the developer. “Josef Reinstein” is the alias of Dr. Abraham Erskine (Stanley Tucci), the scientist who created the unrepeatable Super Soldier Serum in Captain America: The First Avenger. A more stealthy detail, however, is that the name of the program is labeled “Weapons Plus”, which hints at the clandestine program that gave Wolverine his iconic Adamantium skeletal coating.
A very minor Easter Egg, sure, but still a neat little connection that tied the X-Men to the MCU over a decade before the studio officially acquired the rights.