Continuity mistake: In the scene when Dorothy hands her bible to Desmond on the bus, he is seated on the passenger side. However, after the bus departs, he is suddenly seated on the opposite side. (00:26:45)
Continuity mistake: When the Privates are having their furloughs authorised, Colonel Sangston walks in with Corporal Cannon. Only those two men walk in. Corporal Cannon moves from the doorway to give Desmond Doss his rifle leaving no-one by the doorway. After Desmond refuses to touch the rifle, the Colonel shouts at Desmond. Out of nowhere Captain Glover mysteriously appears in the doorway. (00:48:40 - 00:50:10)
Continuity mistake: The wounds on Desmond's face change size and position when he is reading the bible before they get back to the front.
Continuity mistake: While Desmond and Smitty are training and climbing the wood stairs the sun changes between shots.
Continuity mistake: While Desmond helps Dorothy to climb the hill the sun changes between shots.
Continuity mistake: When Dorothy finds the feather Desmond left in her book, she picks it up with her right hand and pulls the feather out with her left. She then sets the book down. When it cuts to the close up of the feather the feather is now in her right hand and the book has magically jumped of the table and into her left hand.
Continuity mistake: When Desmond and Dorothy are on the mountain top and kiss, the side to which they tilt their heads switches back and forth several times as the camera switches between looking into the face of one then the other.
Continuity mistake: When the Japanese man at the end stabs himself in the stomach, in one shot we can see there's no knife in his stomach.