Just caught the last 20 min or so of the film on TCM, and at the end, Ben Mankewicz mentioned that when shooting wrapped in Berlin, Rosselini invited them cast back to Italy for a dinner/visit, and many/most of them did not really want to even go back to Germany when the visit was over. They were there on visas, but many of them "slipped into the streets of Italy and quietly disappeared" so they wouldn't have to go back...although, he said, many eventually were captured and sent back to Germany...
Really interesting film and (real-life) backstory, one I'd been totally ignorant of until just now seeing it...for sure want to see the entire film sometime soon.
Reminds me, in a kind of casual way, of a Montgomery Clift film from the very same year: "The Search" (which was Clift's first real film, incidentally)...although the tone is for sure a hell of a lot lighter, it is also set in war-torn Berlin, and one of its central characters is a little lost refugee boy, an Auschwitz survivor....the boy reminds me of the Edmund character a bit. http://www.imdb.com/title/tt0040765/
Mankewicz also said that Rossellini said that the boy bore a striking resemblance to Romano Rossellini, his young son who had died before the film was made.