Although Dr. Harlan Williams' (Chris Noth's) military service is never specifically addressed in the movie, he is seen wearing the insignia of the 45th Infantry ("Thunderbird") Division on one of his uniforms. This unit fought in World War II and the Korean War.
When Ann is walking down the street in LA in 1953 with groceries there is a gay pride flag behind her. The gay pride flag wasn't created until 1978.