Sylvester Stallone, Jason Statham, Jet Li, Dolph Lundgren, Terry Crews, Randy Couture, and Arnold Schwarzenegger are all back from the last movie. And there are a TON of new additions.
Wesley Snipes plays a founding member of the team that they have to bust out of prison . . . which is a tongue-in-cheek reference to the fact that Snipes couldn't participate in the first two movies, because he was locked up for his tax troubles.
Antonio Banderas adds comic relief as a commando who's always desperately wanted to join the team. And Mel Gibson is Stallone's old partner . . . he cofounded the Expendables, but turned bad and became an arms dealer with a vendetta against him.
In order to deal with the new threat, Stallone recruits some young, fresh blood . . . including Kellan Lutz, MMA badass Ronda Rousey, and boxer Victor Ortiz.
And finally there's Kelsey Grammer as an old friend of Stallone's who helps recruit the new members . . . and Harrison Ford as the CIA handler behind their assignments.
Unfortunately Chuck Norris doesn't show up again, and Bruce Willis punked out when it came time to film . . . but it sounds like they added more than enough muscle to over-compensate.