When Hanshiro first arrives at House Iyi he states that his master's house fell in 1619 (as translated in the subtitles) but he actually says Genna 5 (which is correct according to the calendar used in Japan at this time). Japan did not adopt the Gregorian calendar until 1873. The film was released and the subtitles made after Japan had already adopted the Gregorian calendar, however, so it made more sense for both Japanese and foreign audiences to render the year in Gregorian style.
After Motome's seppuku, when Omodaka steps forward and chops Motome's head off (supposedly), he visibly stops his swing before striking Motome's neck (naturally, since real swords were used).