Just before the American attack on the hill, the commanding officer is pointing out positions on a 3D clay model of the hill with his M4 bayonet. He lays his bayonet on the table and covers it with a paper map, then steps over to the radio man in conversation. He then steps back to the map table and the paper map has disappeared.
All of the American officers are wearing their bright rank insignia and Infantry branch insignia. In reality, officers rarely wore these items in the front lines because they identified those men as leaders, who then became prime targets for the enemy.
Real American hand grenades had a narrow yellow band painted around the tapered upper section to quickly identify them as live fragmentation grenades. However, the grenades in the movie have no such bands, indicating that they are either inert training grenades or movie props.
King company had a number of Republic of Korea (ROK) soldiers mixed in with its American soldiers. For example in S.L.A Marshall's book, "Pork Chop Hill" on page 150 he states, "The other two ades] fell about 25 yards behind Kuzmick, wounding three of his three Koreans." Korean soldiers are mentioned many other places in the book, which is the source for the movie.
All the deuce-and-a-halfs--2.5-ton trucks used to transport troops--and jeeps have shiny enamel paint jobs. Combat vehicles have flat (non-shiny) paint jobs. Light can be seen reflected on the wheels and many other parts of these vehicle, which would make them a perfect target for enemy fire.