The Tin Flute is set in 1940, which influences the characters' attitudes and opinions of World War II. Because Canada is part of the United Kingdom at the time, Canadian soldiers are fighting in Europe. The United States will enter the war much later, in December 1941. While the military and related munitions manufacture have provided employment, the ripple effects have not spread throughout the economy. Many of the characters are still mired in extreme poverty.

While many Canadian men have joined up and already seen combat in Europe, others are staunchly opposed to the "English" war that they do not see as relevant to them. This vast difference of opinion is shown by the argument between Azarius and the snack bar owner. Similarly, the lack of consensus about the war's value, even as a means of employment, is shown by Emanuel's conversation in the restaurant with three former school friends; he has joined up and phrases his motivation as idealistic, but they remain unemployed and unconvinced of the value of being a soldier.

The limited benefit of the war in helping many families is most clearly shown in the female characters. Rose-Anna, in particular, already has eleven children and is expecting another; her son enlists mainly for the income it brings. Faced with imminent eviction, her inability to afford even a cheap toy—a tin flute—for her son encapsulates the effects of poverty. Florentine fortunately has a job as a waitress, but she bears a heavy financial burden because her father is unstable. Her infatuation with a soldier leads to her pregnancy and then to marriage with a different man after the soldier moves on.