Lieutenant Veli never wears any headgear as a part of his uniform. As an Ottoman officer he would have worn a fez or a fur cap.
Lillie refers to the war as World War 1, it was known as the Great War and some years after the end of the war it was known as the war to end all wars. It wasn't known as WW1 until after WW2 began.
The crowd voices at market and other scenes were in Arabic language, while the formal language at that time was Turkish.
The island with the 10th Century church on the Lake Van is referred, or rather pronounced several times as the "Ahtamar Island" whereas the correct name is "Akdamar".