Though the victory parade would have taken place after the armistice in November 1918, it is bright and sunny and people are dressed for warm weather.
In an early sequence set in 1918, Constance Bennett is shown playing a phonograph record on the Victor label--but the label is the "scroll design" Victor didn't use until 1925.
Although the story takes place during the First World War, 1917-1918 and the years immediately thereafter, all of Constance Bennett's clothing and hairstyles are strictly from 1931, as are those of the female extras and passersby.
Toward the end of the movie, only Doris' shadow appears on the wall as she goes to her son's crib. Just before the scene cuts, the shadows of two hands rise up from behind the crib. They are probably the hands of the director giving visual signals to Bennett for her movements in the scene.