Trivia: The idea of helicopters was not necessarily new in WW2, but effective designs were not made until after the war; there is evidence from some literary sources (one of them being a book named "German Secret Weapons of WW2" or something like that) that the Germans did indeed conduct experiments and designs on this vehicle type.
Trivia: Patrick McGoohan committed himself to appearing in "Ice Station Zebra" whilst he was filming his famous TV series "The Prisoner". However, as is well known, "The Prisoner" went massively overbudget and seriously behind schedule. As a result, McGoohan had to leave filming of "The Prisoner" in late 1967 for several weeks, in order to appear in "Ice Station Zebra". This is the reason why several episodes of "The Prisoner" have McGoohan either absent or only in previously filmed flashbacks and inserts...McGoohan could not be filming both "The Prisoner" at Elstree, and "Ice Station Zebra" in Hollywood at the same time.