The opening title says it is set in December 1942, the season its name indicates..
There is a lot of 'snow' on the ground at a funeral. But the trees are green.
The blood on Milner's shirt is unconditionally identified as the blood of his murdered wife, while in 1942 this was simply impossible due to the lack of DNA blood testing in the arsenal of forensic medicine. This analysis was first used in criminal investigations only in 1985.