You are making the mistake of believing that "cinema is cinema, history is history". Cinema and history were both tools of politics ever since their creation. Three examples:
1. During the reign of Otto von Bismarck German historians published hundreds of books, brochures and what-not, that showed Slavs as primitives deserving only to be enslaved by the "enlightened Europeans". Their main theory was that Slavs were descendants of mud-eaters from the swamps of Ukraine! Such scientific theories were used as justification for expanding German power. Even today some German journalists writing for history-oriented periodics are claiming "Slav-inferiority" books from the XIXth century as their knowledge sources.
2. I'm sure you are familiar with the "Poles charged tanks with swords" stereotype. The reason why it is so prevalent today is because during the war, and few years after it, nearly every single German movie was depicting exactly this falsified image of Polish military. Should you visit 9gag today, search for posts about Poland and WWII, you would still find comments claiming that Ułani were charging Pz.Kpfw. with lances and swords! And most of those comments come from Americans! It's not because Americans are inherently stupid, but because german propaganda is still alive, thanks to certain publications.
3. Lately another piece of German propaganda from the war began surfacing. Official German justification for invading Poland in 1939 was that Poland performed the act of aggression, entering the Reich and taking over Gleiwitzsender (Radiostacja Gliwicka). The incident at Gleiwitzsender was a provocation staged by the Germans, and it was a well know fact... for some time. But lately a British politician, Nigel Farage, said more or less that he doesn't want more Poles in UK because they started WWII by storming Gleiwitzsender!
History and historical facts have always been tools for politicians to (selectively) use. Nobody is denying that there is no "perfect nation" without flaws. The problem, however, is that lately there were suspiciously many film and book publications focusing solely on the plight of Jews and Poles oppressing them. There are rotten apples everywhere, but focusing only on them is, by an average viewer, understood as a presentation of the entirety of said nation.
What is especially annoying, is the double standard. It is all nice and good when we show Poles being the oppressors, even though Poland lost relatively more population during the war than any other country. But God forbid saying anything wrong about the Jews! Doesn't matter that they were slaughtering Polish civilians in Koniuchy, Naliboki, Ryki, Świńska Wola etc. and that they formed a majority of Security Service after the war.
In fact most of the world never give the place a thought.
That is entirely untrue. Due to Poland's geographical location, it is the axis of almost all European East-West power plays.