History Film / ItHappenedHere

* RareVehicles: Actual vehicles, uniforms and weapons from the era were used, all donated by various collectors.

* PropagandaMachine: A newsreel gives a revisionist history of British/German relations, ending with British and German soldiers having a snowball fight on the Russian front.

* BritishNazis: For once justified. There are even actual British Nazis!

* LiteraryAllusionTitle: ''Literature/ItCantHappenHere'', a 1935 novel by Sinclair Lewis about a totalitarian government taking over the United States.
* MoralMyopia: A female IAO Commandant reprimands Pauline for not showing "loyalty to the English people" (e.g. failing to denounce her friends). Also the IAO Political Leader at a funeral for a BlackShirt:

** Even more appalling when you realize that Colin Jordan, the man playing him, was a ''real'' British fascist.

* ReassignedToAntarctica: Pauline is demoted and sent to the countryside, a move she initially welcomes as the country hospital has none of the fascist paramilitary trappings of the ambulance corps. [[spoiler:She then discovers the hospital is being used to euthanize foreign slave workers who have contracted TB.]] Also seen when a 'friend' tries to denounce Pauline for secretly trying to get some morphine. Fortunately her superior has just received a phone call announcing his reassignment to somewhere unpleasant (presumably the Russian front) and throws her out of his office.

* TheReveal: When Pauline learns the unpleasant truth about her new hospital.

* ShoutOut: The movie's title is a reference to the book ''Literature/ItCantHappenHere'', a novel deconstructing the notion that Nazi-style fascism can't take root in Western democracies by showing just how a takeover could happen.
* ShownTheirWork: On one occasion a group of [[UsefulNotes/WeAreNotTheWehrmacht Bundeswehr]] tank officers training in Britain were surprised to see German [=WW2=] era soldiers marching through Parliament Square; they inspected the troops and pronounced them "absolutely correct". There also actually ''were'' British SS members. Although the exact name in the film (British Legion of SS) is false, the real Legion of St. George, later British Free Corps, actually existed. However, it never reached more than fifty people overall. Their instigator, British fascist John Amery, was hanged for high treason.

The concept of the film was first developed in 1956 by eighteen year-old Kevin Brownlow, and was eight years in the making -- the longest ever production schedule to date according to the Guinness Book of World Records. It had a cast of hundreds; all volunteers with only two professional actors among them. While trying to find [=WW2=] uniforms for the film Brownlow met sixteen-year old history buff Andrew Mollo, and the two decided to work together on the project. Brownlow would later become a prominent film historian and Mollo a leading military historian. ''It Happened Here'' also launched the career of cinematographer Peter Suschitzky, who went on to such films as ''Film/TheRockyHorrorPictureShow'' and ''Film/TheEmpireStrikesBack''.

* ShownTheirWork: On one occasion a group of [[UsefulNotes/WeAreNotTheWehrmacht Bundeswehr]] tank officers training in Britain were surprised to see German [=WW2=] soldiers marching through Parliament Square; they inspected the troops and pronounced them "absolutely correct".