Paul Rudd tells Jimmy Fallon that 'Quantumania' set had to be shut down over a bunch of manure

Count your lucky stars that Smell-O-Vision never took off. If it had, audiences would probably be making their way to the nearest theater exit, pinching their noses, in the middle of Ant-Man and the Wasp: Quantumania (in theaters this Friday).

Appearing on NBC's The Tonight Show Starring Jimmy Fallon this past weekend, Paul Rudd (who returns to play microscopic Avenger, Scott Lang) peeled back the curtain on the Marvel Studios production, revealing that the mysterious subatomic universe known as the Quantum Realm was brought to life with the Volume technology invented for The Mandalorian. To add an extra layer of texture to the foreground, the production hauled in large quantities of dirt, which turned out not to be dirt at all.

RELATED: ‘Ant-Man and the Wasp: Quantumania’s Evangeline Lilly shows Jimmy Fallon how to properly shrink

"They try and make it feel as much like the Quantum Realm and we have something to react to," the actor told Fallon. "It was crazy to go into these sound stages and it looked like you were in outer space, something wild ... They try and have as much practical stuff as possible; you really feel like you're on a planet or you're in some weird space."

He continued: "One of the [sets], we went in, and there was dirt all over the floor. We were shooting with like 150 other creatures and people and I was like, 'It doesn't smell good at all.' Throughout the day, it was kind of getting worse and worse, and the next day it was overbearing. We realized they probably got a deal on the dirt because it actually wasn't dirt — it was manure. They actually had to shut it down for a day and bring in some new dirt ... The Quantum Realm just reeks!"

Watch the full interview below:

Written by Jeff Loveness (an Emmy-winning veteran of Rick and Morty), Quantumania will introduce audiences to Jonathan Majors' Kang the Conquerer, a more dangerous variant of the Time Variance Authority founder we first met in the Season 1 finale of Loki. With Thanos defeated, Kang is next in line to terrorize the Marvel Cinematic Universe, whose next big crossover event in 2025 bears the rather ominous title of Avengers: The Kang Dynasty (Loveness is writing the script for that, too).

Peyton Reed returned to close out the Ant-Man trilogy, overseeing an insanely stacked cast of Rudd, Majors, Evangeline Lilly, Michelle Pfeiffer, Michael Douglas, Kathryn Newton, David Dastmalchian, Katy O'Brian, William Jackson Harper, and Bill Murray.

Ant-Man and the Wasp: Quantumania officially kicks off Phase 5 of the MCU this Friday, Feb. 17.

All episodes of The Tonight Show Starring Jimmy Fallon are now streaming on Peacock.