Eric Bana is driven around in a Volvo 245 Station wagon, but the only time he is shown inside the car it is obviously a sedan model with a sloped roof and rounded rear windows, quite different from the boxy 80s Volvo seen from the outside.
Michael does not have the DFC ribbon on his dress uniform.
It is set in 1982 but the car is a 1988 one.
Michael at the cabin is wearing a dress uniform as he is preparing to leave. Also Rose is shown closing up his duffel bag. He didn't have a duffle bag or a uniform when he arrived.
When Michael prepares to leave Rose and re-join the war, he dresses in his formal uniform and prepares to go. But he hasn't shaved, which is part of the look of the actor who plays him (Jack Reynor) and not "regulation" for the services during World War II.