Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is a war fantasy movie with some pretty good action and a good cast. It's one (the first, I think) of a series of movies made in the 1980s with ex-soldiers who return to Southeast Asia to rescue Viet Nam war soldiers missing in action who are thought to be prisoners of war but were never released when the war ended. These movies are all fantasy attempts to squeeze out a heroic victory from a failed war. The setting is always that the government doesn't care about its veterans, and that the mercenaries are heroes and patriots because they are willing to risk their lives to rescue them, but these movies have been critisized for exploiting the hopes of Vietnam war veterans and the families of soldiers missing in action by giving them unrealistic hope that they might still be alive. I looked it up, and no MIAs were ever been found alive, and its now 50 years after the end of the war. That doesn't mean they were never kept in secret camps, just that they were never found and returned. But just because the characters are trying to do something that is unrealistic, that doesn't mean this is a bad film. It's worth watching. And there's also a very interesting snakebite scene that avoids most of the dumb cliches of movie snakebite scenes.
Most of the film takes place in 1983, after retired Colonel Jason Rhodes (Gene Hackman) has spent a few years trying to find his MIA son. After he learns of a secret POW camp in Laos just north of Thailand, he gets funding from a rich man (Robert Stack) who also has an MIA son, and puts together a small group of ex-soldiers, Dirty Dozen style. He trains them, then brings them to Thailand where they sneak into Laos with the help of three Laotian rebels, intending to rescue any Americans they find held prisoner in the camp.
When the group gets to the POW camp, it looks deserted from above, so two men, Wilkes (Fred Ward) and Blaster (Reb Brown), sneak down to check out the camp. We learned earlier that Wilkes was a tunnel rat in Viet Nam who had a terrible experience that made him claustrophobic. When they realize that one of them needs to crawl through a metal drainage pipe to get to the camp, Wilkes chooses to go. Blaster, who knows about Wilkes' fear, gives him a charm he keeps around his neck to protect him. Wilkes crawls into the pipe, looking terrified, and when he encounters a snake that bites him on the hand, he screams for help.
Wilkes wrestles with the snake until he is able to cut its head off with his knife. (We saw him pull the knife out during training.) He throws the body of the snake to Wilkes, who picks it up then tells Wilkes that it's OK, the snake isn't poisonous, which in his mind means that the charm protected him. I guess if you believe in lucky charms, logic isn't important. Wilkes then takes his bloody hand and continues crawling through the pipe to the camp.
The snake we see is a live Burmese Python, a non-venomous species found throughout Southeast Asia, so they got those two things right. And extra credit for not trying to make us believe that a harmless snake is a venomous one that kills instantly, as we see in other movies. In fact, everything about the snake scene is believable, which is rare in a movie - even the beheading. If you are in a dark tunnel and a snake bites you, your first instinct is not going to be to identify the snake. You're going to try to kill it quickly. And he doesn't cut the head off in one swipe of the knife as we usually see in movies. He has to saw it quite a bit. That's because we see a knife actually cutting through a real python's body, not a fake snake. The shot is a close-up, so you can't tell if it's Fred Ward's hand holding the knife or if the snake is dead or alive before being cut. I suspect that someone else is cutting up a dead snake, but I don't know that for sure. I think the snake scene is used to get Wilkes over his claustrophobia. A snake biting your hand wouild be terrifying enough to make you forget your other problems.