Spider-Man: Into the Spider-Verse spoilers ahead. There is a lot to keep up with in Spider-Man: Into the Spider-Verse. I mean, we're talking seven Spider-People's worth of information and backstories. But, once the actual movie ends, we get an even deeper look into the Spider-Verse in the post-credits scene. There's time travel, a reference to a popular meme, and yet another Spidey.
After Into the Spider-Verse ends, the start of the credits features music and even more cool graphics. After this, though, there's a moment mid-credits where one of his quotes comes up on screen in memory of Stan Lee, who died just weeks before the film's release. Then, there are a ton more credits (a lot went into this movie), and at the very, very end we get a new scene that possibly hints at the future of Sony's Spider-Man plans.
The scene starts with text that reads, "Meanwhile in Nueva York". Then, we see a version of Spider-Man named Miguel (played by Oscar Isaac), who says, "Let's go back to the beginning one more time." (According to ComicBookMovie.com, he's speaking to his holographic assistant Lyla.) At this point, Miguel travels to Earth-67 and pops up across from a traditional-looking Spider-Man.
Miguel and the other Spider-Man are shown pointing at each other, and if you're not a big comics or Spider-Man fan, you will probably at least recognize this as the Spider-Man Pointing at Spider-Man meme. In the post-credits scene, there's a couple funny "What's going on here?!" lines from the Spider-Men and then the whole thing ends.
So, what was going on there? Who's Miguel? Earth-67? Huh? According the Marvel Wikia, Earth-67 is the reality in which the 1960s Spider-Man cartoon took place. Basically, there are a ton of different realities in which Spider-People exist — as shown in the movie — and Earth-67 is one of them. The Marvel Wikia explains that in a comic set in Earth-67, that reality's Spider-Man is surprised to find that Miles Morales from Earth-1610 and Peter Parker from Earth-12041 show up in his world.
As explained by Know Your Meme, the image used in the meme originates from a 1967 episode of the Spider-Man cartoon. This would be the world in which the post-credits scene is taking place, although Earth-67 as a "place" was an idea that came about after.
Miguel is Miguel O'Hara aka Spider-Man 2099 aka the Spider-Man of the year 2099. He was created in 1992, according to CBR, and has a different costume and different abilities from the other Spider-People. Comic Vine explains that Miguel worked at Alchemax — which plays a big role in Into the Spider-Verse as far as the different realities coming together — but he decides to fight against big corporations like it and others once he gains his powers.
This is all very complicated, but the point is the post-credits scene presents yet another Spider-Man with added humor provided by the meme reference and hints at future movies and stories involving either just Miguel or Miguel and other Spider-People. There is already reportedly a Spider-Verse sequel in the works, according to The Hollywood Reporter, as well as a spinoff with all female heroes. It will be interesting to see what comes next, and whatever it is, you can bet it'll have a post-credits scene, too.