All the signs in the so-called "Ho Chi Minh" city are in Thai, which doesn't look even remotely like Vietnamese. Vietnamese language is written in the Western alphabet, with accent symbols over some letters. Thai has its own alphabet, quite indecipherable to Westerners.
The two MPs who appear early on the film are named Mangold and Pennycate. This is an homage to Tom Mangold and John Pennycate, authors of the book THE TUNNELS OF CU CHI, which was an instrumental reference source for the screenplay.