Polish vehicle registration plates from before 1937 should have red letters (KL in this case, meaning Kielce voivodeship), not black (what is difficult to learn from black and white photos).
A steam locomotive used in the movie is Ty42-107 (Polish version of German WWII Kriegslok class 52 freight locomotive), with markings changed to Pn12-107 - which was a Polish designation of Austrian express locomotive kkStB 310 class - but the highest number in this class was Pn12-22. Repainting a designation alone was a worthless effort, because those few people, who recognize that Pn12 was a prewar class, clearly see, that the locomotive is not Pn12, but a wartime Kriegslok.