The film posits a fictional representation of the last days in the life of Edgar Allan Poe. In reality, no one actually knows how Poe spent his last days, his death being shrouded in mystery. He was found, delirious, on the streets of Baltimore on October 3, 1849, wearing clothes that were not his own. On the night before his death, he was reported to have repeatedly called out the name "Reynolds." He died on October 7, 1849, as depicted in the film. All medical records, including his death certificate, have been lost.
When talking about navigation techniques Poe (Cusack) mentions he went to West Point and was expelled. This is historically correct, Poe was a cadet at West Point during Robert E. Lee's tenure as Academy Superintendent prior to the Civil War.
The man who is cut in half by the pendulum is Rufus Wilmot Griswold. In real life, upon Poe's death, Griswold wrote an unfavorable obituary for Poe which was first published in the October 9, 1849 issue of the New York Tribune. Additionally Griswold wrote a biographical article about Poe painting him as a depraved, drunk, drug-addled madman. Writers Ben Livingston and Hannah Shakespeare wrote Griswold's fictional death scene as revenge. After Poe's death, Griswold claimed to be Poe's literary executor promising to share any profits with Poe's family which he did not. However, he attempted to destroy the author's reputation. Much of what he wrote were half-truths and outright lies, parts of it were lifted almost verbatim from Edward George Bulwer-Lytton's The Claxtons and his description of the fictitious Francis Vivian. Griswald also claimed he had proof in the form of some of Poe's letters. These were later found to be forgeries. Griswald's mendacious portrayal of Poe appeared in biographies about him for the nearly two decades and formed most people's impression of the man.