This article contains spoilers for Spider-Man: Across the Spider-Verse
Spider-Man: Across the Spider-Verse features plenty of very important realities that are both integral to the movie and to the wider multiverse itself. With Sony Pictures Animation paying homage to comics, movies, TV shows, and video games, every universe had the potential to appear.
The story beats and characters in Across the Spider-Verse require very specific realities in the narrative. The film ultimately just wouldn't be the same if any of these Earths weren't included in some way. It's important to note that most of the Earths here are the B versions from the films and not the A versions from the comics. In this context, Marvel's most famous reality is Earth-616B, starring Peter B. Parker.
10 Earth-616
Regardless of the Marvel project, Earth-616 will always be an integral universe for storytelling. Earth-616 is the reality in which the main Peter Parker from the comics lives. Without that reality, Across the Spider-Verse simply wouldn't exist in its current form.
The Peter B. Parker from the Spider-Verse series is from Earth-616B and that reality very briefly appears. This is the most traditional variation of Spider-Man and his world put to screen, featuring a very comic-accurate Mary Jane and the debuting Mayday Parker. This reality is integral for Miles, as Peter B. Parker becomes one of his closest allies and his integral mentor.
9 Earth-688
Although Spider-Man might be one of Marvel's most influential heroes, Across the Spider-Verse teases a major anti-hero. While the Spot travels across dimensions, he sticks his head into a shop in Earth-688. There, he speaks with Mrs. Chen from the Venom films.
The Venom universe's inclusion in Across the Spider-Verse might be minor, but it's majorly important. It further ties Sony's Spider-Verse together, also linking to the MCU. The live-action and animated worlds can cross over. With Spider-Man bonding with a symbiote likely becoming a canon event, Earth-688 might be the catalyst for that in Miles' world.
8 Earth-199999
Earth-199999 is the reality known to viewers as the base of the Marvel Cinematic Universe. Although in-universe it's titled Earth-616, in truth 199999 is more accurate. Miguel O'Hara briefly mentions the escapades of the Spider-Man and Doctor Strange from Spider-Man: No Way Home, which have already caused problems across the Spider-Verse.
While Earth-199999 might have led to some of the anomalies that Spider-Man 2099 is having to solve, a character from this universe is also included in Across the Spider-Verse. The Aaron Davis that was established in Spider-Man: Homecoming makes a cameo as a captured Prowler. Clearly, the villain will be making future live-action appearances.
7 Earth-131222
One of the funniest sequences in Across the Spider-Verse features an unexpected and extraordinary version of Spider-Man. Earth-131222 introduces audiences to LEGO Spider-Man. Animated with a stop-motion aesthetic, this universe only makes a brief few appearances.
However, LEGO Spider-Man is one of Miguel's best agents for a reason. The Spot makes an appearance on Earth-131222 and LEGO Spider-Man reports in with Spider-Man 2099. Without this information, Miguel might not know just how powerful Spot was becoming. Thus, this toy-based Earth actually has an important role in the plot.
6 Earth-138
Spider-Punk has become a fan-favorite character in Across the Spider-Verse. Hobie's whole personality, and his fantastic suit, have been defined by the British punk rock scene on Earth-138. Spider-Gwen found solace on Earth-138 and the world has shaped a unique iteration of the web-slinger.
Spider-Punk and his anarchist ideology help save Miles Morales. If Earth-138 didn't exist, then neither would Hobie. Without Hobie, Miles might have never mastered his venom-blasting powers enough to escape from Miguel O'Hara and the rest of the Spider-Men. Earth-138 has a big influence on the narrative despite actually appearing very briefly.
5 Earth-50101
Earth-50101 is one of the realities that Miles travels to after chasing down Gwen Stacy. It features a mash-up of Mumbai and Manhattan known as Mumbattan and is home to Pavitr Prabhakar, a firm ally of Gwen and Miles who later joins Ghost-Spider's exclusive multiverse team.
Earth-50101 also helps establish the idea of canon events. Miles steps in at the last minute to save Prabhakar's local Police Captain. He isn't supposed to and Spider-Man India's universe is forever changed. If Miles stayed away from Earth-50101, perhaps Miguel would have dealt with him differently.
4 Earth-928
Into the Spider-Verse film was one of the best animated movies of all time. But, Across the Spider-Verse tried to up the ante by introducing Spider-Man 2099 and Nueva York. Miguel O'Hara and the Spider-People HQ both exist on Earth-928.
A huge portion of Across the Spider-Verse takes place in the futuristic backdrop of Earth-928. The reality shapes Miguel, who has already traveled across the Spider-Verse in search of a better life. The harsh reality is a reflection of the very man who stands in Miles' way.
3 Earth-42
Earth-42 is one of the most important realities in Miles Morales' journey. The spider that bit Miles and gave him his powers originated from Earth-42. But it was never supposed to make its way to Morales' reality. The very fact that it bit Miles created an anomaly that led to the death of Peter Parker.
Earth-42 is an Earth without a Spider-Man and therefore has experienced a huge wave of crime. The Miles and Aaron Davis of Earth-42 are criminals in their own right, with Miles taking on the moniker of Prowler. Across the Spider-Verse concludes with Spider-Man captured by the duo and stuck on Earth-42.
2 Earth-65
Earth-65 is Gwen Stacy's home where she became Ghost-Spider/Spider-Woman. Very little was seen of Gwen's Earth appeared very little in the first film, but Across the Spider-Verse kicks off by showing her canon event: the death of her Peter Parker.
Earth-65 provides the emotional core of the movie, as Gwen and her Police Captain father attempt to make amends after she reveals her secret identity. Each time Across the Spider-Verse returns to Earth-65, new narrative arcs form which are integral to the rest of the film and Spider-Gwen's journey.
1 Earth-1610
Earth-1610 is the Earth that's featured the most in the Spider-Verse saga. It's the home of Miles Morales, the hero of the story and the Spider-Man audiences have followed since his origins. Across the Spider-Verse uses Earth-1610 to ground Miles with family-driven conflicts, while setting up the antagonist of the piece.
The Spot also originated on Earth-1610 due to the multiverse machine that the Kingpin had built, exploding in the first film. Earth-1610 is an anomalous reality, as Peter Parker should never have died and Miles should have never taken his place. The third installment will return to Earth-1610 as Miles attempts to save his father's life.