Royal Opera House, Valletta shown in the film was destroyed by a bomb in WW2 (1942).
In the movie the Maltese flag is missing the George Cross. The George Cross was not added to the Maltese flag until 1943. The George Cross was awarded to the people of Malta by King George VI in 1943 to "bear witness to the heroism and devotion of its people" during the great siege where the Maltese people withstood an onslaught of bombings by the German and Italian forces in the early part of WW2. Even as they were cut off from food and ammunition supplies, the Maltese people did not surrender and some historians have said that if the Maltese people did surrender, it could have changed the course of WW2 to the Axis's favor.