The Hunley's torpedo was much simpler in design than it is in the movie. In the film, the sub rams the torpedo into the side of a ship, attaching the explosive to the hull. Then the sub backs away and detonates the bomb with a rope. In real life, the sub rammed the torpedo into the ship, detonating the explosive on impact. This was determined by the archaeologists in 2013, as they preserved the Hunley.
Actually, there were only 8 crew members, not 9.
In the movie, the Hunley attacks the Housatonic from the port side. In real life, the sub came in on the ship's starboard side.
The double eagle Dixon's wife gives him is accurate for the period but the image is backwards.