Factual error: When Captain Yelland is shown the reconnaissance photo taken over Pearl Harbor by his own plane, it is identical to the historic photo from Commander Faraday's files. If you look at the picture, you can see 2 torpedo wakes heading towards the ship in the center of the photo. This is confirmed by the Discovery Channel's "Death of the Arizona" program. The photo was taken just as the attack began, and at this time in the movie, the attack was still a day ahead.
Factual error: Pearl Harbor is said to be 280 miles away from the USS Nimitz. An F8 Crusader on a recon mission to the harbor reports unusual shipping traffic, and that he will make another pass for a close-up series of photos. The CAG then immediately states the F8's ETA (estimated time of arrival) back to Nimitz is 12 minutes. At its maximum speed of 1,225mph, it will need to skip the second pass entirely to have any hope of returning in 12 minutes.
Factual error: Aboard the Navy helicopter Senator Chapman slugs a Navy seaman in the head, knocking the sailor out cold on the first punch. But the sailor was wearing a helmet, hard on the outside and padded on the inside. It's not all that easy for an average person to knock someone out bare-handed; it's probably nearly impossible to do so through a helmet that's designed precisely to protect the head from hard impacts.