How accurate is this movie?

I did. It was of little help.

After the war, Fellers played a major role in the occupation of Japan. Among his duties was liaison between HQ and the Imperial Household. Soon after occupation began, General Fellers wrote several influential memoranda concerning why it would be advantageous for the occupation, reconstruction of Japan, and U.S. long range interests to keep the Emperor in place if he was not clearly responsible for war crimes.[20] He met with the major defendants of the Tokyo tribunal. In their research and analysis of events and considerable controversy about the time period, according to historians Herbert Bix and John W. Dower, Fellers—under an assignment by the code name "Operation Blacklist"—allowed them to coordinate their stories to exonerate Emperor Hirohito and all members of his family.[21][22] This was at the direction of MacArthur, now head of SCAP, who had decided that there was to be no criminal prosecution of the Emperor and his family.

General Fellers, who came from a Religious Society of Friends family (commonly known as Quakers) and attended the Quaker-affiliated Earlham College,[2] was instrumental in the selection of Elizabeth Vining, an American Quaker educator, as tutor to the Emperor's children. Ms. Vining was followed after 4 years by another Quaker educator, Esther Rhoads.[23]

In 1971, Emperor Hirohito conferred on Fellers the Second Order of the Sacred Treasure "in recognition of your long-standing contribution to promoting friendship between Japan and the United States."[24]

Fellers' role in exonerating Hirohito is the main subject of the 2012 film Emperor.