Some things that bothered me about the prologue were first, the editing. I found the points at which it jumped between scenes to be annoying. First time I watched it I couldn't even remember being shown, after all of that stretcher-bearing, whether the stretcher actually made it onto the boat. On second watching I realized it sort of looked like Fionn & Aneurin were on a boat and they no longer had the stretcher with them. I think you were supposed to get the impression that they were hoping to just stay on that boat, a mental argument between salvation vs following orders and waiting their turn. But it certainly was not clear. That's a big thing and I think to not even make it clear that they were on the boat was confusing. The part with Mark Rylance suffered from a lack of clarity of his lines, particularly the most important line about his intention to pilot his own boat to Dunkirk. From having read about Dunkirk, I know the boat owners could let the military commandeer and pilot their boat to Dunkirk, but many civilians chose to pilot their own boats into battle to help save the soldiers. To me, this is central and huge to the whole story of Dunkirk. I have seen many people saying they could not understand the dialog in that spot. That is quite a loss.