Movie takes place in year 1944. Short scene from the front line is showing a T-54/T-55 tank. These tanks entered production in 1947.
Hair-style and sideburns of actors are obviously '70's style. Officers of army in the 1940's definitely wouldn't have that sort of style.
The movie shows Russia attacking on Mannerheim's birthday. In reality Mannerheim's birthday is on 4th of June. The Normandy landings, which is mentioned, happened on D-day 6th of June and USSR began their Karelian offensive on 9th of June.