At the market the Arab sells his wares using dinars. Dinars were not legal tender in Palestine, they used Palestinian pounds.
The movie is set in 1937, ten years before the discovery of Qumran where the assassination occurs.
Incorrect jewelry on female characters for the time period, especially Jenny Seagrove's character.
During the boat scene starting around 16 minutes in, several female extras in the background here and there can be seen with obvious 1980s hairstyles (big, teased, loose). There is a glaringly obvious hair and costume mistake at exactly 17:25.
It is impossible for Westholme to shoot Hassan or even be in the marketplace. The only way she can do that is if she had chased him through the busy streets like what Dr. King did.