The PC version originally required a permanent internet connection even in single-player. In November 2011, Ubisoft removed this copy protection and the game only requires a one-time activation since then.
References to the game
Silent Hunter 5: Battle of the Atlantic
was parodied in an episode of "Die Redaktion" (The Editorial Team), a monthly comedy video produced by the German gaming magazine GameStar. It was published on the DVD of issue 08/2010.