Iron Man pointed out a significant flaw in The Flash's powers, revealing that they wouldn't work in the Marvel Universe in the same way.

Tony Stark once pointed out a considerable flaw with The Flash's speed powers, as Iron Man admitted that not only did they not make any sense from his perspective, but they wouldn't work the same in his universe. In JLA/Avengers #3 from Marvel and DC Comics, the heroes worked together in an epic crossover, as Stark watched Barry Allen use the cosmic treadmill. However, he quickly realized that his powers might not be useable in certain worlds since different physics would prevent him from accessing them.

The Flash's powers come from the Speed Force, an extradimensional energy source granting the hero a wide array of abilities, including super-speed, energy manipulation, and even a healing factor. By tapping into the Speed Force and his super-speed, The Flash and certain powerful speedsters can also travel through time and different realities with the Cosmic Treadmill. However, when Iron Man first saw the time-traveling device in action, he pointed out a considerable flaw that would happen if Flash tried to use it in the Marvel Universe as opposed to the DC Comics reality he's from.

Related: The Flash’s Speed Force Unlocks A Green Lantern Ring’s True Potential

In JLA/Avengers #4 by Kurt Busiek, George Perez, Tom Smith, and Comicraft, the Justice League and Avengers worked together to restore reality and take on the villain Krona, who has merged the DC and Marvel Universe - causing the world around them to change continually. Iron Man and The Flash concoct a plan to get to Krona's stronghold, using Thor's hammer Mjolnir and the Cosmic Treadmill to break through his shields. However, when they combine their powers, Tony Stark points out that the Flash's speed time-travel powers have one considerable flaw: they wouldn't work the same in his world.

While their plan is a success, Iron Man sharing that The Flash's dimensional travel powers wouldn't work on his Earth shows the speedster might have trouble if he ends up in a dimension where physics differed from his everyday reality. Tony Stark admits converting speed into a vibrational wave that shifts the temporal-dimensional locus "wouldn't work back home" in the Marvel Universe. It's a flaw in The Flash's powers he needs to consider should he ever end up stuck in a world where he needs to escape via interdimensional travel.

The Flash's speed powers might not work the same in other worlds, such as the Marvel Universe. Still, since comic books play fast and loose with the rules of powers, especially regarding speedsters and time travel, Tony Stark's comments should probably be taken with a grain of salt. However, The Flash should remember Iron Man's concerns should he find himself about to travel to the Marvel world from the DC Universe, as he could end up stranded in a dimension he can't escape.

Next: Marvel Calls Out Batman's Most Overused Villains

Lead writer for Screen Rant's comic team. Liam.M@screenrant.com. Find me on Twitter @LiamRMcGuire for comic news and reporting.