George Sewell plays two parts in this movie; he is a German officer, seen at the film's climax, and also briefly plays Adolf Hitler.
The actual title for raid was Operation Anthropoid.
Since the film was set in Czechia, the filmmakers made use of Czech army equipment such as OT81 half tracks which are very similar to their war time predecessor, the German Sdkfz 251/1.
The Sten gun seen in the movie is a Mk 2. In real life, the assassins were given the (slightly inferior) Mk 3. But what caused the gun to jam is now thought to have been rabbit food. Short of food, the Czechs bred rabbits - turning weeds into protein. They collected bits of foliage wherever they found it, to take home for the bunnies, carrying it in whatever they had available, including a briefcase with a broken-down-to parts Sten gun. The Sten fires just as the bolt is closing - called "Advanced Primer Ignition". If a bunch of weeds, grass whatever STOPS the bolt from closing.... it doesn't go "bang".
This movie was one of the few productions (besides several made in Russia and Yugoslavia) which took the time and the effort of duplicating WW2 German Tiger tanks. The only other American production who did this was Kelly's Heroes (1970), until Steven Spielberg did the same for his movie Saving Private Ryan (1998).