Marvel may have taken a long time to bring Spider-Man and X-Men under its cinematic universe (the latter still pending), but the studio referenced both of these as early as their first movie. In a never before seen deleted scene from the 2008 (yes, the first) Iron Man, we see Nick Fury referencing Spider-Man and the Mutants in his now iconic post-credit scene in which he reveals the Avenger initiative to Tony Stark. Marvel Studios President Kevin Feige debuted the clip at the 2019 Saturn Awards and you can see the leaked version below:

Understandably, Marvel Studios used the term radioactive bug bites to get away from copyright issues while mentioning Spider-Man. But using Mutants was still unexpected, as under Fox’s agreement, Marvel was barred from using any terms related to mutants in their films. It’s the reason both Quicksilver and Scarlet Witch were referred to as “the twins” or “the enhanced” without explicitly referencing any of the X-gene, Mutant or any of the X-Men lingo.

Had this line’s use been permitted, it would’ve been game-changing for the MCU in many ways. It implied Spider-Man’s existence in the universe already, with Peter Parker having gained his powers. Considering the only iteration old enough to exist at that point would’ve been Tobey Maguire’s Spider-Man, could Sony and Marvel have worked out a deal to bring him into the MCU? Also, with the mention but without a deal, we would never have had Tom Holland as Peter Parker since Parker would’ve been too old around the time of Civil War. Finally, mentioning mutants but not bringing them in would’ve shrouded their absence in future movies in mystery.

It’s probably for the best an alternate take was used. Back during the production of Iron Man, it was reported that Samuel L. Jackson had given multiple takes with different lines, out of which the producers chose the best ones. I’m sure they never intended to use this version and only shot it for fun. Still, it’s entertaining to see something new from the movie that kick-started the MCU in its entirety.