Everyone knows that when you watch a Marvel film or TV show, you're not just watching a Marvel film or TV show - you're merely experiencing one smaller piece of a much larger jigsaw. Events in Captain America can affect what happens in the next Ant-Man, the actions of the Agents of SHIELD are impacted by whatever Tony Stark has been working on in the films. "It's All Connected", they say.
So with the release of Doctor Strange, what does this newest blockbuster add to the Marvel Cinematic Universe? Read on to find out.
Warning! Major, life-ruining spoilers ahead. So don't blame us if this ruins your cinema-going experience.
So, umm. This is pretty awkward but here's the thing - there aren't actually many references to the wider MCU. Stephen Strange wasn't using some clever Stark technology during surgery, and the Ancient One didn't go to school with Daredevil. The film's Dark Dimension is not the same thing as Thor 2's Dark World.
But there are some meagre pickings.
Just in case you didn't realise this was part of the MCU, one of the establishing shots of New York after the opening sequence clearly shows Stark Tower - or the base of the Avengers. This is in, umm, Stark contrast to the Netflix shows which despite taking place in the same New York haven't bothered to edit out the real life MetLife building which stands in its place. Sadly in the third act, though we see NYC getting rather trippy, we don't see any of the action taking place on the side of the tower or anything too clever like that.
The most important crossover was undoubtedly the revelation that the Eye Of Agomotto - the green glowing pendant that Strange wears around his neck - is one of the Infinity Stones. These are, in Marvel lore, the six stones that existed before the creation of the universe that give the bearer some pretty insane powers and are what we expect Thanos to be ultimately trying to acquire in Infinity War.
So far in the MCU we've seen all but one: The Space Stone is the Tesserect, the McGuffin in Captain America and the first Avengers film. The Mind Stone was given to Loki by Thanos, and currently resides on Vision's forehead. The Reality Stone currently belongs to The Collector, and the Power Stone currently belongs to the Nova Corps - both as sen in Guardians of the Galaxy.
The Eye of Agomotto is the thought to be the Time Stone - leaving only the Soul Stone unaccounted for in the MCU. We can perhaps expect it to make an appearance in one of the forthcoming films before Infinity War.
It wouldn't be a Marvel film without a cameo from Stan Lee. In Doctor Strange, he's only seen very briefly as the camera cuts to him sat on a bus during a fight scene, oblivious to the action taking place in the Mirror Dimension. While not an MCU reference, he's reading The Doors of Perception by Aldous Huxley. Published in 1954, the book is an essay about his experiences taking the psychoactive drug mescaline - which ties in nicely with the themes and aesthetics of the film. (The other good news for Stan Lee fans who might be worried about his, umm, advancing age, is that he's apparently already shot cameos for the next four Marvel films, so we'll be seeing more of Stan for some time yet.)
Perhaps the best reveal in the film was the mid-credits sequence, in which we see Strange in conversation with none other than Thor, who reveals that he's back in New York looking for Odin. This is clearly an allusion to Thor: Ragnarok, which is due to hit around this time next year. Most intriguingly Strange promises to join him in his search - revealing a casting decision that has somehow not already been leaked. Hulk is also set to appear - which means that the forthcoming film could be the weirdest team-up since, well, Civil War.
And then there is the actual post-credits sequence, which appears to hint at what we can expect from the inevitable Doctor Strange 2. Clearly incensed by Strange meddling with powers he doesn't understand, and angry at the Ancient One's betrayal, Mordo is seen hunting down the other magical person in New York who sent Strange on his journey to Nepal. He kills him because there are "too many sourceres".
And as far as we can tell... that's it. If you've spotted anything else, let us know in the comments.