Eventually, it seems, every senseless waste of life gets its own gauzy tear-jerker. That’s about the only way to justify “The Flowers of War,” in which the veteran Chinese director Zhang Yimou revisits the Nanjing massacre of 1937 by making something resembling a backstage musical, with breaks for the occasional ghastly murder or rape....

“Flowers” has received bountiful publicity for being expensive, state-approved and Oscar-submitted, buzz that got louder last week when the film’s British star,...