The Avengers was successful in defeating Thanos in the Endgame thanks to the Quantum Realm to travel through time and require the Infinity Stones but the MCU had almost decided not to go with that story which got the fans thinking how could have this plot work without such important element.
The Quantum Realm was introduced to the MCU in 2015’s Ant-Man as a dangerous state of reality and potential consequence of using Hank Pym’s size-altering Pym Particles without failsafe measures. And Scott’s journey there at the end of Ant-man and the Wasp proved invaluable to the Avengers, but the Ant-Man film series began earlier in the MCU under a different director’s visiting, meaning that Avengers defeat Thanos another way.
Scott got trapped in the Quantum Realm which saved him from Thano’s snap since laws of time and space do not apply there the same way they do in MCU’s main reality. He didn’t even age once in 5 years and perceived them as only five hours which further helped him and the Avengers to discover Quantum Realm’s use for time travel.
It was revealed in The Story of Marvel Studios: The Making of the Marvel Cinematic Universe, Peyton Reed revealed that he added the Quantum Realm concept to the film, as a last-minute addition! (P.S: Reed took over the film from Edgar Wright just a year before its release)
Edgar Wright’s Version of the Film Had Never Set Up Endgame!
Edgar Wright’s version of Ant-Man was way too smaller and character-focused than Reed’s take. Wright had put Hank Pym and Scott lang in focus and the final ties to the MCU were added by Reed. According to a significant departure from the comics, Wright’s Hank had nothing to do with the creation of Ultron, and a change was coordinated with Joss Whedon for Avengers: Age of Ultron. Even Scott’s fight sequence with the Falcon in Avengers’ facility was added by Reed.
Quantum Realm was also absent from Wright’s version and was added by Reed after Wright left. That leaves us wondering how would have Scott Land defeated Yellowjacket in Wright’s version.
Ant-Man Would Still Become An Avenger Without The Quantum Realm
Hank Pym was a founding member of the Avengers in their original Silver Age debut, but that wasn’t the case in the MCU. There were plans to have The Wasp take over Black Widow’s place and Ant-Man was never intended to become the team’s founding member. But thanks to his knowledge and use of the Quantum Realm, he joined the team.
Considering that Wright’s version didn’t have the concept of Quantum Realm, Scott could have still joined the team. All the original six members of the Avengers survived Thanos’ snap but weren’t the only heroes who survived. Scott could have simply survived regardless of Realm and still joined the Avengers thanks to his friendship with Captain America, Falcon, and Hawkeye. His skills and gear could have been invaluable to the Avengers.
Here’s How Endgame Would Have Still Done Time Travel Without The Quantum Realm!
Endgame could have still achieved time travel through other means and allowed the Avengers to carry out their “time heist” to undo Thanos’ snap. The other methods which have shown in MCU were Agents of SHIELD, Runaways, Loki, and Doctor Strange.
And of course, Tony Stark would have devised a new method of time travel too. The TVA had advanced time travel technology but would have never interfered in Endgame. With Endgame being Tony Stark’s final appearance, it’s fitting that it would be his genius key element to the Avengers’ reversal of the snap. And Scott would have still been integral to the plot as he was part of Avengers’ New York 2012 team!