You're right, in the film it was "Danny Velinski", "Louis Sedgwick" and "Willie Dickes" who escaped, I believe all Australian/British. But in the film there were Americans among the escaping officers while in reality there were none. Dutch ace Bram van der Stock who was one of the three that made it, didn't agree with the film, especially the story and asked not to be included as a character. His character was replaced by the fictional Sedwick. I think that sais it all about the film. Why the Norwegian were not include is unknown to me.
The book you mention is that written by Paul Brickhill? That one at least includes the right names.