When asked if the movie will live up to the hype, Jeremy Renner said with a straight face, "I'm pretty certain of that."
Chris Evans later added that the end will be "satisfying" for fans.
While Iron Man himself, Robert Downey Jr., said this film would be Marvel's crowning achievement, he also joked to "bring a bag lunch" because it's clocking in at almost three hours long.
The Hulk aka actor Mark Ruffalo said bring a "box of Kleenex and a diaper."
Marvel Studios head Kevin Feige has said in the past that this will be the final run for certain characters. It definitely seems like Captain America star Evans is saying goodbye, having tweeted a heartfelt message to fans earlier this year. He did not confirm anything Monday.
"This has been an enormous part of my life, it will follow me till the day I die," Evans said after explaining this is the end of a decade of films, culminating in "Endgame," while new stars like Captain Marvel will take the studio into the future. "You try to prepare yourself for the completion and then the day came and it was more than I thought it was gonna be."
"It got me, I'm an emotional guy," he added about possibly saying goodbye.
None of the stars have seen the final cut.
"We really all are as in the dark as all of you," Scarlett Johansson said.
Chris Hemsworth apparently has a battle waging within his household, telling "GMA" that only one of his kids thinks he's cool as Thor, while the others like Wonder Woman.
"So, they sleep outside," he joked.
The interview ended with a preview, which included Thanos using the infinity stones again?!
"So, let's get them," Brie Larson's Captain Marvel says. "And use them to bring everyone back."
"If we do this, how are we going to know it's going to end any differently than before?" Bruce Banner says.
"Because before you didn't have me," Captain Marvel replies.
"Endgame" is out April 26.
ABC News and Marvel are both part of parent company Disney.