Character mistake: When Garrison is leaving the house to question Clay Shaw on Easter Sunday, his wife is complaining about his working on the Sunday, and at one point calls Garrison 'Clay'.
Character mistake: In the scene before the New Haven concert, when Jim is talking with the reporter/ love interest about his school history, she comments that Jim attended the University of Florida. In actuality, Jim attended Florida State University.
Character mistake: We see in a flashback (so, early 1600s) the protagonist with his mother in Ruen, back in motherland France. She tells him she is praying to St. Joan (d'Arc; they are in front of a statue of hers). Joan d'Arc wasn't canonized until the 20th century. You could argue that in the eyes of the laymen she was already considered a saint. However, her son does not object and considers her a saint as well, doubling down on the statement even later on in Quebec when he does not have to humour his mother, and he is a Jesuit. He obviously should know better. (00:35:25)