Yes, as you rightly say, "nothing on the scale of Germany and Japan". The fact is that the armed forces of both those countries regularly committed massacres of prisoners and civilians, as a deliberate policy and with the full knowledge of their respective High Commands. This is nowhere near to the situation in the Western Allied forces where such behaviour was a rarity and usually due to a local breakdown in discipline rather than acting on orders.
I asked that particular question of redneck, "Which massacres by Allied troops in WW2 , and of whom, would you particularly like to see portrayed?" because he seems to be under the impression that such behaviour was normal and commonplace across all armies and combatants in WW2, when it manifestly wasn't.