It seems Sony and Disney were talking to each other.
Despite the fact that Disney owns Marvel, they don’t own the rights to one of Marvel’s top sellers, Spider-Man, and thus the forthcoming Amazing Spider-Man and the recent Avengers films were pretty much always seen as being in different realms of the Marvel universe, but apparently Sony (which owns Spider-Man) and Disney were actually thinking about a crossover.
It was nothing as big as seeing Peter Parker strolling into the middle of the battle in New York City, or even a flash of a possible Avengers candidate file with his name (though I don’t see why that couldn’t have happened), but rather the two were talking about including the Oscorp building into the Manhattan skyline. You know, somewhere close to but not imposing on Stark Tower. The building was designed by J Michael Riva, who is also responsible for design of the Iron Man movies (and who recently passed away) so there was already some design continuity in that regard, and it seemed like a quick plug and play situation. In fact, according to Latino Review this is how close things were to going down:
That design overlap, and the stunning look of the Oscorp Tower (seriously stunning) was enough for Marvel Studios and Sony to have the discussion about inserting Oscorp into The Avengers skyline. The Unified Marvel Manhattan Skyline almost existed.
By the time the Oscorp building was fully designed, The Avengers digital Manhattan was already basically rendered and there was some up-conversion that needed to go down, so – for timing – it was scrapped.
BUT – Sony and Disney were going to let this happen. THAT’s the key thing here. Timing just didn’t work out.
The key is that last part. The two rivals were actually going to let this crossover happen, which could open up the future for small Easter Eggs like this. I wouldn’t expect Peter Parker to be teaming up with the Avengers any time soon, but do keep your eyes open in forthcoming Disney/Marvel films as well as Sony’s Amazing Spider-Man series to spot any indications that these two storylines (and major companies) occupy the same universe after all.