That familiar, weathered face belongs to Chuck Norris, and whatever Sylvester Stallone, the architect of these films, paid him to return to the big screen, it wasn’t enough. Mr. Norris arrives just as the blood baths and leaden dialogue are beginning to grow tedious, and his deadpan self-parody is pretty darn funny. More important, it gives you permission to laugh at the rest of this mindless movie, which is the only way to choke it down.

As with the first “Expendables,” in 2010, Mr. Stallone has assembled a roster of prominent action stars, many of them noticeably past their prime, and a preposterous amount of explosives and heavy weaponry to enact a formulaic good-triumphs tale. Returning cast members include Bruce Willis and Arnold Schwarzenegger, who have a bit more to do here than they did in the first film, as well as Jason Statham, Dolph Lundgren, Randy Couture, Jet Li and Terry Crews. Newcomers, in addition to Mr. Norris, include Yu Nan (yes, women can be Expendables too), Liam Hemsworth of “The Hunger Games” and, playing a villain named Vilain, Jean-Claude Van Damme.

Mr. Stallone’s character, Barney, leads a group of old-school mercenaries who are dispatched by the mysterious Church (Mr. Willis) to retrieve something from a safe in the wreckage of a crashed plane. Vilain is there too, one of the Expendables dies, and the mission morphs into one involving payback and plutonium.

Mr. Stallone directed the first film but here turned that job over to Simon West “so that he could focus more on the writing,” the film’s press notes explain. (He shares a screenwriting credit with Richard Wenk.) That extra attention to the script produced plenty of those earnest, Stallone-esque lines that you can only hope are intended humorously, because if they’re not, they’re just embarrassing.

Until Mr. Norris shows up, the script’s efforts at sly comedy don’t work all that well, relying on obvious inside jokes and references to the various stars’ previous work. Mr. Norris’s character, Booker (also the name of his character in the 1978 film “Good Guys Wear Black”), works those same angles but is somehow much funnier. From his arrival until the film works its way to the inevitable mega-confrontation in which the bad guys shoot with stunning inaccuracy, and the good guys don’t, the movie is pleasantly dumb fun if you watch it with the right mind-set.