Character mistake: When Ryan is recreating the chess game he and Mandy played, he has the chessboard setup incorrectly. He has the dark square on the lower right corner when it should be the white square. He was a junior grand master and would know better, especially since he had the board set up correctly when they were playing.
Character mistake: Mike is holding and talking about his .59 caliber flintlock and refers to placing a percussion cap on it to fire it. A flintlock does not use a percussion cap.