One year after the movie's release the real Erich Gimpel was released from jail and he moved to South America where he live all his life until he died in 2010 in Sao Paulo, Brazil.
Billy Cole is based on the real life American Nazi Agent William Curtis Colepaugh, who, while didn't speak German, joined Germany in 1944. He was also arrested and collaborated with the FBI, where he was telling about himself and Erich Gimpel. Like Gimpel he originally condemned to death, which under Harry Truman was changed to jail for life until he was released in 1960, 4 years after the movie's release.
Final film of Chiqui Jonas.