The General was never identified by his first name in the film. In the credits he is referred to as Maj. Gen. Kreipe. In real life he was Majorgeneral Heinrich Kreipe. Calling him Karl, as many sources do, seems to have been an invention of the Rank publicity department.
According to Michael Powell's book, "Million Dollar Movie," the film's composer, Mikis Theodorakis, considered it shameful that a story about Cretan resistance fighters would be told by anyone other than Cretans. He told Powell and Pressberger that they were both political "interlopers" -- a label he also used in describing Patrick Leigh Fermor.