- "She's got a thing for retards."
- ―After En-Joo says that he likes Diaz's sister.
Diaz first appeared sipping a bottle of beer on John Rambo's boat, heading downriver. After En-Joo told Reese to stop singing, Reese remarked that En-Joo didn't appreciate the arts. Diaz then chimed in, saying that En-Joo doesn't like anything. En-Joo quipped that he likes Diaz's sister, and Diaz responds by saying that she has 'a thing for retards', throwing his half-full bottle of beer into the river, apparently bored with it. Diaz then pulled out a knife and began whittling a small piece of wood, asking Lewis what the Reverend said to him. Lewis started to complain about how the missionaries were stupid enough to go into Burma in the first place.
Like Reese, Diaz was heavily tattooed and wore a cloth wrapped around his head as a hat. He wore a brown tee-shirt with a utility belt and gray pants. When they visited the abandoned village the Tatmadaw ransacked, Diaz continually protested Schoolboy's idea that they should fire on the approaching soldiers who were about to kill civillians after gambling on their lives, however he did support the idea of searching the camp for the missionaries.
But then Rambo arrived and killed all of the soldiers in a matter of seconds with his bow and arrow, much to the chargin of Diaz, who angrily claimed that the Tatmadaw would hunt them down after they realized that the soldiers weren't going to come back, which everyone agreed with. During the final gunfight, he was sprayed by flaming gasoline from a boat-mounted T-148 flamethrower, but was still alive at the end of the film. His fate is ultimately left unknown but it is likely that he survived.
- Diaz's weapon of choice was a DSA SA-58 OSW carbine with a scope and folding stock. Diaz's version has the Type III Metric receiver (with minimal machining cuts). The DSA SA-58 OSW, is offered with the Type I receiver (more cuts, lighter weight, but not as strong). Thus it is suspected that the SA-58 OSW in the film is a build up of a previous FAL Type III receiver with DSA OSW Parts.
- Rey Gallegos gained thirty pounds for the role of Diaz.