In the first few scenes of “Snatched,” Emily Middleton (Amy Schumer) loses her retail job and her rock ’n’ roll boyfriend. Those are the high points of the movie, quick and nasty riffs to remind you of “Trainwreck” and raise your hopes for something similar. Those hopes are both fulfilled and disappointed.

Like most popular big-screen comic performers, Ms. Schumer is committed to consistency, or at least to exploiting a successful and familiar persona. She has become more or less what Will Ferrell was a decade and a half ago: the likable embodiment of various forms of human unpleasantness, a soft-bodied clown whose immunity to shame represents an appealing kind of innocence. Emily is self-absorbed, lazy and rude, but also so lacking in true meanness or guile and so dogged in her pursuit of shallow pleasures that she’s kind of fun to be around. Even though she drinks too much, says obnoxious things and misbehaves in other ways — killing two people, for example, one with a shovel and the other with a harpoon — it’s impossible to get mad at her, or even seriously annoyed.

That’s her mother’s job. “Snatched” is an intergenerational buddies-on-the-run movie, a strangely popular subgenre nowadays. Emily’s mom, Linda, is played by Goldie Hawn, who has been funny for a good half-century (going back to “Laugh-In”) and who is cruelly and inexplicably denied that privilege here. Linda, long-divorced and devoted to her two children (Emily’s toxic-nerd brother is played by Ike Barinholtz), functions as an uptight, anxious foil to her wildly undisciplined daughter. In principle that may be a slightly stale premise. In practice it’s just dull, and it’s frustrating to see Ms. Hawn robbed of the opportunity to be silly.

Supplemental silliness is supplied, instead, by Mr. Barinholtz, by Wanda Sykes and Joan Cusack (as a pair of intense tourists), by Christopher Meloni (as an Amazonian adventurer) and by Bashir Salahuddin (as a State Department bureaucrat). The story is nowhere near as hilarious as the director, Jonathan Levine, and the screenwriter, Katie Dippold, would like us to believe. (And not up to the standard of “The Heat” or “Ghostbusters,” both of which Ms. Dippold was also involved in.)