- If the graphic and language content is restricted at the beginning, the camera is zoomed in at the shadows on the wall. Also, at the MG part, at the left, there is a Japanese officer executing a Marine in a hut, but with the content restricted, there is no one in the hut but the conversation can still be heard.
- If the player runs into the first machine gun hut before the remaining enemies are eliminated and stand beside the active machine gunner, he will not notice the player and continue firing. If the player then waits for the Marines to proceed further up the river, the gunner will run all the way back to the starting section of the mission, oblivious to the player chasing him (unless the player ventures too close).
- Sometimes, after Rooker is stabbed by the "fake death" soldier, his body moves slightly, making it look as if the sword was stabbed into the ground beside Rooker.
- The title of this mission, Semper Fi, is short for 'Semper Fidelis', which means 'Always Faithful'; the motto of the United States Marine Corps.
- The achievement 'Saved Private Ryan' is obviously a direct reference to the film, Saving Private Ryan. To earn the achievement/trophy the player must rescue Pvt. Ryan from a flaming banzai charger.
- If the player looks closely at Pyle once he and the Japanese officers are dead, the player can see the slash mark on his neck, and the player can see that his eyes are fine and that there is no trace of any burn from the cigarette.
- On the Wii version, where the bright light shines at the dead soldier booby trap, the light does not blind the person briefly. All the enemies will be visible during the flash.
- When the player meets up with the reinforcements, there is a person named Sgt. Pepper, a direct reference to the Beatles' studio album Sergeant Pepper's Lonely Hearts Club Band.
- On the Wii version, sometimes the Katana-wielding Japanese soldier will drop an Arisaka while he is tumbling to the ground. If the player is quick enough, one can press and hold the reload button to get it, once the player regains control of Miller.
- During a co-op mode, it is possible for some players to stay at the beginning of the level as long as one player goes forward. If the players get through it, when the flare goes off it will affect every player regardless of their location, even if they are indoors.
- In the Wii version, the Japanese officer at the start is wearing a hat.
- In the Wii instruction booklet, the player can see a screenshot from the pause menu, and the objective is to secure the village.
- Alex Mason's bio reveals that his father was a WWII Veteran and a recipient of the Purple Heart for wounds received during action at the Makin Atoll.
- If the player uses the first MG, Sullivan will act like there is another gunner.
- At the end of the level the player can see Roebuck and Sullivan moving their mouths, but nothing can be heard.
- In the Wii version, Pvt. Cook disappears after the player is rescued.
- When the Marine gets caught in the booby-trap at the temple, the player can turn right instead of going straight on. When standing next to the rest of the temple, it is possible to hear a deep, unintelligible voice muttering something.
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