I expected to love this. But I didn't. I'm no expert, but even I could see a lot of obvious faults. I'm not just talking about things like modern buildings (which are very evident), but the lack of atmosphere. At the start of the film, the beach is crowded, quite rightly - but after that, it's pretty empty when we see it. Where are the heaps of ruined vehicles, etc? All dead bodies are completely intact. There's no blood at all. The Germans are never called the Germans ("the enemy"). How are we supposed to believe that over 300,000 got back to England? Apart from the near empty beaches, we almost only see people NOT making it home. As for the "little ships", apart from the Mark Rylance one, thirty or so of them arrive all together as a neat flotilla to cheer up Kenneth Branagh. And how long does a Spitfire take to come down after it runs out of fuel?
