During the battle of Tenaru, you can clearly see the blank rounds in the belt magazine in a close-up shot of the machine gun team.
The quote Leckie recites, "Without a sign, his sword the brave man draws, and asks no omen, but his country's cause.", while he and his fellow Marines eat before landing on Guadalcanal, is from the ancient Greek poet Homer.
SPOILER: The Japanese soldier that draws his sword and is killed by Sledge is a sergeant, according to the rank insignia on his collar. The soldier that he nearly takes the gold teeth from later is a 2nd Lieutenant.