The last time Joel and Ethan Coen dropped by Hollywood, they nearly burned the place down.

In their gleefully bilious 1991 comedy, “Barton Fink,” John Turturro plays the title sap, a New York playwright who goes west to work for Capitol Pictures, where his Louis B. Mayer-like boss insists straight-faced that “the writer is king!” It’s a cruel joke, one that the Coens play out as Barton is engulfed in flames and madness. As apocalyptic as a Nathanael West hallucination, “Barton Fink” felt like the testament of two filmmakers who, however much they loved movies, were happy to torch the industry. Yet here they are in “Hail, Caesar!,” back on the lot and cracking jokes.

If this were anyone other than the Coens you might think that success and a couple of Oscars had mellowed them. Not likely. “Hail, Caesar!” is one of those diversions that they turn out in between masterworks and duds. It’s a typically sly, off-center comedy, once again set against the machinery of the motion-picture business. And, as usual with the Coens, it has more going on than there might seem, including in its wrangling over God and ideology, art and entertainment. Some of it is familiar and satisfyingly funny, even if there are laughs and bits that seem as if they were written to amuse only the Coens and the Turner Classic Movies crowd. (Love the Loretta Young nod!)