During the movie we get to see all popular models of Saab and Volvo. However the registration plates on some cars are too modern. One example is the light blue Volvo 142/144 that has a sign issued more than 20 years after the car was made.
In movie Ove is 59 years old, his mother died when he was 7 (character Ove 7 year). If movie time is set in 2015, his mother died in 1963. After funeral we see his father car is right hand drive, Sweden was left hand drive country until 1967.
But Swedish cars had the driver on the left, even when driving on the left.
When young Ove is on the train track the train approaches behind him. The train isn't blowing its horn to warn the child. The engineer would have made sure the danger was given proper warning. The same issue when the train is passing by the other trains when Ove's father receives the paper with Ove's school grades. The engineer would have blown the horn mightily.