The 'flaws' noted above are not really that serious. Firstly, yes the sudden appearance of Willem suggested a cut scene, a frequent occurrence in many movies, owing to pacing and duration considerations - could have been better handled, but it was explained briefly. Secondly, the various groups of Dutch soldiers, some fighting each other, was fully explained several times in the dialogue - the city has been infiltrated with German fifth columnists, and nobody is sure who is friend or foe! In the battle scene by the canal the late arrivals have been sent by the man at the government department, to help the 'good guys'. Thirdly, you are correct that the OFFICIAL Dutch resistance was not yet organised, but the resistance fighters in the story are early volunteers who are trying to hamper the German occupation of Amsterdam, and will no doubt form the nucleus of the resistance movement that would soon follow. So, you see, not really serious flaws at all!