Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
At the end of part one of this 9 hour adaptation of Larry McMurtry's Pulitzer Prize-winning novel, a group of cowboys is crossing a river in south Texas on horseback when all of a sudden one of them, the one who was afraid to cross, is attacked by a bunch of vicious "water moccasins" that come out of nowhere after all of the other cowboys and cows have already crossed at the same spot, as if that was even remotely possible. (We are also expected to believe that the snakes would attack him first, instead of his horse.) Worthy of a scene from any of the worst snake horror movies, we see him thrashing around in the water grabbing handfulls of snakes that are writhing all around him, until finally one bites him on the cheek to end part 1.
One cowboy says he's never seen anything like it, and another comments that the recent storm must have stirred up a "nest" of the snakes, in a lame attempt to rationalize the event. This is an ignorant, but sadly common belief - that snakes congregate into large "nests" or "dens" outside of winter when they often share the same shelter because it is below the freezing temperatures. (See the Movie "Mud" below, and almost any of the snake horror films where herds of snakes invade a town for more of this folly.)
Of course, I could be wrong - Harry Greene, the herpetologist who literally wrote the book on snakes, highly praises this film and the book in his autobiography, so perhaps this and all the other snake myths are actually real.
Most of these are fake snakes, but it looks like they did put a few live ones in the mix to add some movement, but they were most likely harmless watersnakes which are similar to Water Moccasins (Cottonmouths.)
If you search for "Lonesome Dove Snake Scene" on YouTube you might be able to watch the scene. Try this one.
As part 2 begins, several cowboys jump or ride into the river to help him, and for some reason the visious "nest" of seething moccasins leaves them alone even though there are still a few rubber snakes floating on the water. Tommy Lee Jones yanks a snake off the kid and tries to see how far he can throw it. (This marks the invention of the sport of moccasin tossing, which thankfully never became popular despite the prevalence of snake-killing festivals in Texas called "rattlesnake roundups.") For some odd reason, nobody shoots at the snakes, like they usually do in Westerns. (They shoot at the snakes in the book, so why not here?) When the kid is taken out of the water, we see a whole bunch of double fang-marks on his chest and face, because that's what all snake bites look like in the movies.
I give some credit to this film because these cowboys don't go around randomly shooting rattlesnakes during the long duration of the film and of their journey just to prove how tough and ready they are, as a lot of movie cowboys do. They save that kind of horrible indiscriminate killing for Native Americans and for lynching outlaws, which, terrible as it is to see, is most likely exactly what happened in the old West.
The film opens with a shot of two pigs eating a dead rattlesnake (it looks like a real dead Western Diamond-backed Rattlesnake) on a front porch.
Robert Duvall kicks them off the porch, throwing the back half of the snake which they left behind after them. We don't see who killed the snake, but we assume it was the pigs, who go on to be two of the stars of this much-beloved movie (which relies too much on unbelievable coincidences and cows crossing too many rivers for my liking.)
Later in the first of the four episodes, we see a cook skinning a Western Diamond-backed Rattlesnake, one of four that are hanging off one of the ropes to his canvas shelter.
When one of the cowboys asks what it's for Robert Duvall says it's supper, that it'll make a good stew.