Goofs

"Doctor Novak" as a Pole would spell his surname "Nowak". The W in Polish is pronounced as a V.

Near the beginning, a group of German Prisoners of War are seen marching through the village under escort, singing the Horst Wessel. Several of the prisoners are wearing the Wehrmacht eagle on their field blouses. As POWs, these insignia would have been removed to avoid distressing the villagers, and to show that they were non-combatant.

Sergeant Brooke is collecting money for the football pools, and asks Foyle for "a tenner". In England this means ten pounds, which would have been a huge amount of money during wartime, two or thee weeks' pay for an average man.

No, he asked for a tanner, not a tenner. Sixpence.

Foyle has been presented in this and earlier episodes as a chess lover. However he and Dr. Novak, whose uncle was "champion of Poland", play a bizarre opening (with a possible move sequence 1. e4 e5 2. b3 b5 3. Na3 Na6 4. Nxb5) that no-one familiar with basic principles of chess would play.