Continuity mistake: During the first battle in the woods, the Union Regiment levels their un-bayonetted weapons and fires a volley at the Confederates. About 3 seconds later, without the order having been given, they are in hand to hand combat with bayonets fixed.
Continuity mistake: When the men refuse to accept their pay, the Colonel tears his paycheck in half. It tears straight down the middle. There is a brief shot of the men, and the camera returns to the colonel. There is a piece of his check in his hand and the tear is now diagonally across the paper.
Continuity mistake: During the fight in the forest, when the 54th go hand-to-hand with the Confederates, Denzel Washington grapples with an enemy soldier on the ground. In one shot the Confederate is hatless; the very next second he is wearing a hat.
Continuity mistake: As the 54th charge Fort Wagner across the beach there is a long range shot of the troops running from the left to the right of the screen. Watch Matthew Broderick. He is holding his large wide-brimmed hat, which he does not wear (or even carry) in previous and subsequent scenes!
Continuity mistake: When the colonel rips his paycheck the sun is shining down on his face, but in the next shot the sun is shining from the side.
Continuity mistake: In the scene where the 54th is on parade, Shaw commands "eyes right" and looks to his right and points his sword down to the right. Then the next shot is a brief shot of his parents and then when they return to Shaw, his sword is pointing up in the normal marching position. There was no audible command to stop saluting.
Continuity mistake: When Colonels Shaw and Montgomery are in Darien, Georgia, Montgomery shoots a soldier (apparently in the heart) for touching a white woman. When the troops are marching out of the town, the soldier who was shot has miraculously felt better, gotten back up and joined the ranks. (01:07:05 - 01:08:55)
Suggested correction: The soldier was shot in the shoulder.