The post-credits scene of 2008's Iron Man famously featured Samuel L. Jackson as Nick Fury, dropping in on Tony Stark to set up not only the Avengers but also the entire Marvel Cinematic Universe. As important as that sequence was, in retrospect, Marvel Studios President Kevin Feige revealed in a video presentation produced for the Saturn Awards that it was nearly even bigger -- and we wish they'd gone with that alternate version, which held the promise of a still more expansive universe.
The scene in the final cut and this newly revealed alternate sequence begin in the same way: Robert Downey Jr.'s Tony Stark returns to his home to find Fury, who presents him with the Avengers Initiative. However, in the alternate version, Fury says, "As if gamma accidents, radioactive bug bites and assorted mutants weren't enough, I have to deal with a spoiled brat who doesn't play well with others and wants to keep all his toys to himself."
The line is a not-so-veiled reference to the Hulk, Spider-Man and the X-Men. While The Incredible Hulk followed on the heels of Iron Man, Sony Pictures was several years away from striking a deal to share Spider-Man, and Disney had not yet purchased Fox, and with the studio, the X-Men film rights It was likely those rights issues that led to the alternate scene being cut, but with the gift of hindsight it's easy to see how great this scene would have been to include.
Part of the magic that makes the MCU work is the interconnectivity between films, frequently achieved through post-credits scenes. While those sequences and offhand references are essential to establishing future properties, the shared cinematic universe thrives on keeping the details vague and acting as if everything is going according to plan when it pans out later.
Kevin Feige confirmou o lançamento de um boxset da "Saga do Infinito" para este ano, com cenas alternativas/deletadas exclusivas. E uma delas já foi compartilhada!— Marvel News (@BRMarvelNews) September 14, 2019
É uma versão alternativa da cena pós-créditos de Iron Man, onde Nick Fury cita os mutantes e a aranha radioativa. pic.twitter.com/YQ7b6S8JWl
Throwaway references like the Infinity Gauntlet seen on Asgard in Thor or the casual name-drop of Doctor Strange in Captain America: The Winter Soldier build up hype for the moment the Easter egg hatches, but in a noncommittal way that is easy to go back on later if it doesn't fit into the larger plans. The Infinity Gauntlet, for example, was disregarded as a fake in Thor: Ragnarok because Marvel wanted Thanos to acquire the weapon by other means.
Offhandedly mentioning Spider-Man and the X-Men before Marvel could acquire or otherwise access the rights (or, indeed, before even Disney acquired Marvel), would have fit the mold of the MCU's Easter eggs perfectly. "Radioactive bugs" and "assorted mutants" may be clear references to specific properties, but they're vague enough that if it never panned out, it wouldn't have really mattered.
Regardless, in 2019 it's easy to see the references would have panned out just fine. Spider-Man already made his debut in the MCU in Captain America: Civil War, and Feige promised the mutants just recently after Disney's acquisition of Fox. Dropping references in their films allows Marvel to give their universe such an expansive feel with very little risk, so the fact that the alternate post credits scene didn't make it into the cut is a shame.
The Incredible Hulk provided an origin for the supervillain the Leader that we still may never see, and Spider-Man: Homecoming hinted at a possible Sinister Six team-up that may never happen, after Marvel and Sony parted company. Neither of those references makes the films providing them any worse just because they don't work out, and with this alternate Iron Man scene we see just how wonderful things can be when they do.