Spoiler warning: Don't read further if you don't want spoilers for "Guardians of the Galaxy Vol. 2."
Pratt (Star-Lord), Zoe Saldana (Gamora), Kurt Russell (Ego), Dave Bautista (Drax) and Michael Rooker (Yondu) discussed the movie with Kimmel, and when the host asked about spoilers, he dropped one of his own.
"I don't know exactly what I can say," Kimmel said, "I know there are reveals and there are secrets, and like, for instance, can I say Sylvester Stallone is in the movie? Is that OK to say?"
Russell, who starred with "Rocky" star Stallone in the 1989 buddy cop movie "Tango & Cash," joked, "Sly's in the movie?"
"I think that's safe to say, yeah," Pratt told Kimmel.
"Can I say Tango and Cash are in this movie together?" Kimmel continued. "Is that all right? Is that allowed?"
"It is now," said Pratt with a laugh.
The news was actually already out there -- director James Gunn has already discussed Stallone and Russell's roles, telling Fandango in late March that Russell and Stallone's roles are "both characters that we've taken a lot of time to develop, and they're a big part of the (Marvel Cinematic Universe) now."
It's been reported online that Stallone is playing Starhawk, also known as Stakar Ogord, who apparently isn't a fan of Yondu. Twitter users had some costume ideas, some playing off of earlier Stallone films.
Also on Monday's show, the cast dodged questions about who among them will be in 2018's "Avengers: Infinity War," and participated in a game show where they answered trivia questions about each other to win bags of ice.
This wasn't the first "Guardians" event on Kimmel's show lately. On Friday, Kimmel ran a clip where show regular Guillermo Rodriguez traveled to the movie's set, receiving acting advice from Pratt and Russell and then shooting a scene as Cop #2.
Unfortunately or fortunately, when the clip was later rolled, Rodriguez was barely visible in his claim-to-fame scene.
The Kimmel clip gave him a much larger role than Hollywood did, and as of Monday evening, has been viewed more than a million times.
"Guardians of the Galaxy Volume 2" opens April 28 in the UK and May 5 internationally.
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