Additionally, the quote in question is used after the effect of Darwin's philosophy played itself out--in essence, the words used by Darwin that were adopted by the "pure race" advocates.
For me, having read both Darwin, and having read some of the Nazi corpus on race theory, your description simply reinforces the fact that the film severely misrepresents Darwin.
Darwin never argued for "pure" human races. Indeed he forcefully argued in exactly the other direction. Darwin concluded for instance that humans are a single, highly variable species; that there is no way to sort humans into distinct races; that for any races one did nevertheless attempt to identify the variation within them swamps the differences between them, and that there are always an array of intermediate characters insensibly connecting all races. Darwin argued all of this in his [i]Descent of Man[/i] (in Chapter VII, "On the Races of Man"), and the Nazis adamantly rejected all of it.
The Nazis acted on the tenets of the race theories of Gobineau, Chamberlain, and the like, as explicitly set out by Alfred Rosenberg and others, that human races WERE distinct, that they originated so, that their racial purity (or that of the "aryan" race) should be restored. This was all incompatible with or foreign to Darwin's teachings and conclusions.
That is an interesting take.
I think the film does a good job of treating Darwin’s words fairly as well as showing how his ideas inspired the Nazis.
Did you see the film? Did you see what the woman who ran the memorial at the Nazi “hospital” said?