Spider-Man: Brand New Day has the chance to finally address one canon-breaking MCU villain theory seven years in the making. The upcoming web-headed adventure will bring Tom Holland's wall-crawler back down to Earth after the Multiversal shenanigans of his last movie. This comes despite the film arriving mere months before the reality-hopping epic that is Avengers: Doomsday. Given its proximity to Marvel's Multiverse mega-movie, some wondered if Brand New Day could feature some dimensional trappings.
One potential otherworldly nugget fans have thought Spider-Man 4 could reintroduce to the Marvel canon is the fact that Jake Gyllenhaal's Mysterio seemingly knew the prime MCU's universal designation long before that was ever actually a part of the Marvel Studios story. Fans may remember Gyllenhaal's fishbowl-helmeted big bad introduced the idea of the MCU's primary universe being Earth-616 in 2019's Spider-Man: Far From Home.
While, at the time, it felt as though the villain was perhaps laying the groundwork for the Multiverse, it was eventually revealed that he was nothing more than a special-effects-using fraud, essentially making things up as he went.
In 2022's Doctor Strange in the Multiverse of Madness, Earth-616 came back into play. As Benedict Cumberbatch's Stephen Strange traversed the Marvel Multiverse, he discovered that his home reality had earned the Earth-616 distinction after a brief interaction with an alternate universe version of Rachel McAdams' Dr. Christine Palmer.
Some took this as a potentially canon-breaking oversight by the MCU, leaving fans wondering how someone who had not interacted with the Multiverse, like Mysterio, could guess the MCU's Multiversal designation. However, others believe there may be more going on under the hood, and it could all be revealed in Spider-Man: Brand New Day (coming to theaters on July 31).
Spider-Man 4's Mysterio Multiverse Theory
There is a popular theory circulating that Spider-Man: Brand New Day could finally justify how Mysterio correctly dubbed the MCU Earth-616.
Rumors of some light Multiversal connective tissue in the upcoming Spidey sequel surfaced earlier, but perhaps in the more fantastical parts of the movie's story, it could loop Jake Gyllenhaal's Marvel villain back into things.
Even though at the time, in Spider-Man: Far From Home, Mysterio's knowledge of the Multiverse was drummed up as a mere coincidence, there is a chance that he knew more than he was letting on.
Of course, this could take the form of the Far From Home big bad being retconned as the Multiversal warrior he introduced himself as to Peter Parker in the 2019 film. Yes, in that movie, it seemed revealed that he was just a jilted former Stark Industries employee using the company's tech to enact his revenge, but could he have been telling the truth to Peter when he introduced the Multiverse?
Brand New Day could bring the character back up, showing that, yes, he did work for Stark, but who is to say that it was the MCU's prime version of the armor-clad billionaire? What if the Multiverse version of his story was accurate, and it was a Variant of Stark he was talking about?
This would iron out those potentially canon-breaking details, finally giving a reason for how he could have accurately guessed the Earth-616 title.
There is also a chance that Mysterio happened across this distinction in his extensive research. He is a man of science after all, who is to say that he never came across the existence of other realities in his various scientific pursuits? This would also warrant the character knowing about Earth-616, retconning the idea that he was a total fraud.
