Page 101. " Two or three ARVN soldiers had built their breakfast fires "

The Army of the Republic of Vietnam (ARVN) was also known as the South Vietnamese Army (SVA), and was in operation from 1955 to 1975. It numbered over 1 million soldiers.

Page 105. " The six greenies were gone "

Greenies is a slang term for the Green Berets.

The Green Berets are a special operation unit of the U.S. Army.

Page 109. " There was a topmost scent of joss sticks and incense "

Joss sticks are paper or wood shells containing herbs and other scented materials. They measure anywhere from several inches long to several meters, and are burned for religious purposes in countries such as China and India.

Page 113. " Rat looked off to the west, scanning the mountains "
View from atop Marble Mountains
Creative Commons Attribution Share AlikeView from atop Marble Mountains - Credit: Dragfyre

These are most likely the Marble Mountains, a cluster of five marble and limestone hills. They are located just south of Da Nang. All of the mountains have cave entrances and numerous tunnels.

Page 115. " for a time the Tra Bong compound went crazy with MP and CID types. "

The US Army Criminal Investigation Command (CID) is responsible for investigating crimes within the Army. Their headquarters are at Quantico, Virginia, and they operate throughout the world.

CID Special Agents conduct criminal investigations ranging from death to fraud. They work with local, state and other federal investigative agencies. CID also provides security and conducts protective service and force protection operations. During battlefield operations, CID’s investigations can include war crimes, anti-terrorism, and other serious crimes.

CID was established during WWI by General John J. Pershing.

Page 115. " maybe with the Montagnard tribes "
Khmer Mountain Tribes' Flag
Creative Commons Attribution Share AlikeKhmer Mountain Tribes' Flag - Credit: http://commons.wikimedia.org/wiki/User:Froztbyte

This term refers to the "mountain people" of Vietnam.  These people lived in the Central Highlands and were considered America's most loyal allies in Vietnam.  Other Vietnamese considered them to be "moi" or savages.  They were largely Christianized.

They helped America in the war in numerous ways, especially by housing troops.  Up to half of the Montagnard tribes were killed fighting alongside American troops. 

Page 118. " our helmets and flack jackets "

A flack jacket is designed to protect the wearer from projectiles, with steel plates, polyethylene or kevlar to absorb their impact.

It is also known as a "bullet proof jacket."

Page 119. " a pair of monks living in a tar paper shack "
Monks
Creative Commons Attribution Share AlikeMonks - Credit: Tevaprapas Makklay

In a land where 80-90% of the population were Buddhist, it was not uncommon to run into a monk.

Page 121. " just like Friar Tuck "

Friar Tuck is one of Robin Hood's 'Merry Men'. He appears in the Robin Hood play from 1475, which is sometimes called Robin Hood and the Knight or Robin Hood and the Sheriff.

In legend, he was formerly a monk of Fountains Abbey, expelled for his lack of respect for authority. The first time he meets Robin Hood he carries him across a river, winning over his loyalty.

Page 125. " Tran Hung Dao's famous rout of the Mongols "
Tran Hung Dao
Creative Commons Attribution Share AlikeTran Hung Dao - Credit: Xiaoao

Tran Hung Dao was the supreme commander of the Dai Viet during the Tran Dynasty, and led the armies that repelled two major Mongol Invasions during the 13th Century.