Extremely Lengthy Creation: It took Rebecca Hall ten years to write the screenplay. Although she finished the first draft in only ten days, it took a decade for her to refine and edit it until she was satisfied.
Fake American: Ruth Negga is Irish and Alexander Skarsgård is Swedish (although he speaks with an American accent naturally).
What Could Have Been: The role of Hugh Wentworth was intended for Benedict Cumberbatch, but was still uncast three weeks into filming, and the time and budget restrictions meant that it would have to go to an actor based in New York. Bill Camp came on board at the last minute.
