Hermann Göring was put on a strict diet by his jailers so he would be fit to stand trial. He ultimately lost 65 pounds (29.5 kilograms).
Michael Shannon's opening statement at the beginning of the trial scene is an exact, although shortened, recitation of the actual opening statement given by Justice Robert Jackson on November 21, 1945, the second day of the military tribunal. To this day, legal experts consider it one of the most influential speeches in the canon of international law and criminal jurisprudence.
Despite how it is otherwise depicted in the film, in reality Hermann Göring was allowed at least one known visit from his wife, Emmy, during his incarceration prior to trial.
Much of Robert Jackson's cross-examination of Hermann Goring is presented verbatim from the actual record of the trial.
The real Robert Jackson was opposed to the death penalty, a position he agreed to defer to the tribunal's judgment. Furthermore the tribunal deliberately chose death by hanging over firing squad to express contempt at the military defendants.