Maggie Lee Chief Asia Film CriticFour days feels like an eternity in “The Eight Hundred,” mainland Chinese writer-director Guan Hu’s monumental, if sometimes unwieldy epic interpretation of the courageous defense of a warehouse by the Chinese Nationalist Army in October 1937. For those with little knowledge of the Sino-Japanese War, the bombardment of facts, action and characters in the 147-minute film can be too much to take in at one go.