Here's what the no mention of the Quantum Realm in Wright's initial drafts of the story. The Quantum Realm is a relatively unexplored dimension inside the multiverse that Scott Lang and the Pym family have been known to travel through. It has also been harnessed to manipulate and travel through time. Without this component of the story, the grand scheme of the MCU so far would ultimately have turned out very differently.
The final version of Ant-Man that Paul Rudd and Adam McKay collaborated on tells the story of Scott Lang: a cat burglar who unknowingly attempts to steal a special suit from Hank Pym’s house, and subsequently puts the suit on to discover some very surprising consequences. The Ant-Man suit, powered by Pym Particles, allows the wearer to shrink very small—or grow very big. Pym designed the technology while he worked for SHIELD, though he later quit when he learned that SHIELD was trying to replicate it behind his back.
Pym was against the replication of his work because he views it as being too dangerous, having lost his wife Janet while they were on a mission together as the original Ant-Man and The Wasp. Janet turned off her suit's regulator in order to shrink between the molecules of a titanium-plated missile, but as a result, she was lost to the Quantum Realm, a space Pym and other molecular scientists know almost nothing about. It's because of this tragic, dangerous brush with the Quantum Realm that Pym swears off being Ant-Man, quits SHIELD., and decades later hires Scott Lang to take up the mantle and prevent a new corporation from duplicating the Pym Particle.
Without mention of the Quantum Realm in Pym's backstory, it's possible Scott Lang may never have found his way into being Ant-Man at all. But assuming that Wright's version of Ant-Man did at least include Lang as the protagonist, there are still several ways in which the omission of the Quantum Realm could significantly impact the MCU further down the line. Here are the big ways MCU Phase 3 would have looked different if Edgar Wright had made his version of Ant-Man:
Ant-Man Would Have Been On Team Iron Man In Civil War
Hank Pym left SHIELD because of his conviction that the Pym Particle was too dangerous to use in the wake of Janet's disappearance into the Quantum Realm. Without this component of the story, it's likely that Pym would still be working for SHIELD in the present day. This would mean Scott Lang's entry into the Ant-Man role would have to look a little different, with the end result being that Lang would probably be working for SHIELD, too.
The existing MCU Phase 3 begins with Ant-Man fighting for Tony Stark's team, not Steve Rogers'.
Ant-Man & The Wasp Would Need An Entirely New Plot
If the omission of the Quantum Realm would impact Ant-Man's storyline somewhat, it would completely change the trajectory of its sequel, villain in Ant-Man & The Wasp: Ghost. Every aspect of this film is steeped in talk of the Quantum Realm and its effects.
This may have worked even without the first film mentioning it, but Wright's version of Ant-Man wouldn't have teed up such a storyline nearly as well. In the alternate version of events driven by Wright's script, Ant-Man & The Wasp also may not have ended with Lang making another experimental trip into the Quantum Realm. This occurs in a crucial mid-credit scene that also shows the Pyms dusting as a result of Thanos's snap. It may be a short moment, but it has massive implications for the rest of Phase 3.
Ant-Man Would Not Have Been Missing In Avengers: Infinity War
As previously mentioned, had Lang fought on Tony's side during Captain America: Civil War, he wouldn't have ended up under house arrest by the time the near-simultaneous events of Ant-Man & The Wasp and Avengers: Infinity War took place. This would likely have put him on the battlefield with all the other Avengers during their various confrontations with Thanos throughout Infinity War. While Lang's presence alone probably wouldn't have been enough to stop Thanos from his successful snap, it would be Lang's absence from the events of Ant-Man & The Wasp during that time that would make the real difference.
Avengers: Endgame Would Not Have Featured A Time Heist
A Wright-directed version of Ant-Man would have had the biggest impact on Lang's five-year stay in the Quantum Realm (as teased in the mid-credits scene of Ant-Man & The Wasp). That time, which is only five hours to Lang, is enough to convince him that the Quantum Realm holds the key to unlocking time travel. He ends up being right, and the Avengers pursue a plan affectionately nicknamed "the time heist" to collect their own versions of the Infinity Stones and bring back everyone Thanos killed.
But if Lang had been fighting alongside the Avengers in Infinity War, he wouldn't have been in the Quantum Realm when the snap occurred, and may not have realized its potential in developing Spider-Man: Far From Home wouldn't have happened—but have serious implications for Phase 4 and beyond.
In short, the original Ant-Man's inclusion of the Quantum Realm into its storyline played a huge role in setting up future Marvel movies. Without this key component, Ant-Man's stories and alliances would have had to change, and Thanos's victory might have been permanent. If Edgar Wright had ended up making Ant-Man, the MCU's Phase 3 would have looked quite different indeed.
Next: What If Black Widow Had Released In Phase 2 or 3? How The MCU Would Change
