When Ant-Man and the Wasp released in 2018, Marvel Studios wasn’t sure when, if ever, it would revisit the microscopic dimension known as the Quantum Realm. So it left behind a little teaser in a blink-and-you’ll-miss-it moment that fans have speculated over for years.

Now, Marvel is finally paying off that Easter egg in a big way, with Ant-Man and the Wasp: Quantumania.

In an interview with Inverse’s Hoai-Tran Bui, Quantumania producer Stephen Broussard, Vice President of Production & Development, says that all of Quantumania — where Scott Lang (Paul Rudd) ventures into the Quantum Realm to rescue his daughter, Cassie (Kathryn Newton) — is building upon a teaser the filmmakers snuck in 2018’s Ant-Man and the Wasp.

“We sort of challenge ourselves at every turn like, what’s the Quantum version of this? How can it feel like the rules are a little skewed and a little different? And the conversations for doing that started when [Ant-Man 2] was done,” Broussard tells Inverse.

Broussard elaborates on a scene from Ant-Man and the Wasp when Hank Pym (Michael Douglas) rescues Janet van Dyne (Michelle Pfeiffer) from the Quantum Realm at the end of the movie. If you look closely, there is a city-like structure in the background. Broussard says this was a peek into the civilizations that actually exist in the Quantum Realm.

“We had put some little Easter eggs when they found Janet that could that could hint to more life and more civilization down there,” Broussard says. “That’s these DVD freeze moments, if you if you want to look for them. I think people have found it before, there’s a moment when Hank finally rescues Janet. And they are making their escape back up to our world in his quantum pod, his sled there. And in the background, you see sort of this domed city, this glass city that kind of mixes in with the background there, but it’s oddly architectural.”

He adds, “And so it’s like, wait a second: Did I just see a bubble of a cell or something microscopic? Was that architectural? Was that actually a city?”

Broussard says the city’s design was directly “inspired by a very specific piece of comic book art.” (Broussard didn’t elaborate on which piece of art, but perhaps he’s referring to this one, from Fantastic Four Annual #25.) “That was laying our marker down for a Part Three, if we come back,” Broussard adds, “You never know if you’re gonna get a chance to do another one. That was us saying what we would do, if we should be so lucky.”

This isn’t the first time Marvel called its shots years before doing so. The superhero studio featured the Ten Rings in Iron Man before spotlighting them in a big way in Shang-Chi and the Legend of the Ten Rings. The end of The Avengers had Thanos make a scary appearance before Avengers: Infinity War. There’s a history of Marvel laying down the foundations for its future, even if the studio openly admits it doesn’t always know if it’ll get to capitalize.

But with Jonathan Majors making his debut as Kang the Conqueror in Quantumania a few years before Avengers: The Kang Dynasty opens in 2025, Marvel is getting a little more confident about knowing where the future is headed.

Ant-Man and the Wasp: Quantumania opens in theaters on February 17.