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 redneck revenge movie with a cast full of, at the time, little-known actors most of whom went on to become recognizable stars - Patrick Swayze, Liam Neeson, Ben Stiller, Helen Hunt, Bill Paxton, and Adam Baldwin. Swayze plays a Chicago plain-clothes cop with a pony-tail mullet who's married to classical violinist Helen Hunt, but he was originally a "mountain boy" from Kentucky, where most of his kin still live. The next of kin of the movie's title is his brother, Bill Paxton, who is killed by the mob. Swayze's brother, Liam Neeson, and the rest of his kin swear to get revenge and kill the guy who killed Paxton, but Swayze has to play by the rules and wants only to arrest him and take him to trial. But after his second brother dies, Swayze reverts to his hillbilly revenge killing roots and takes on the entire mob. The climactic cemetary battle between gun-toting mobsters and a hillbilly army armed with knives, hatchets, bear traps, hound dogs, and bows-and-arrows, is worth the price of admission.
But what about the snakes? First, when Swayze returns to his little Kentucky community for Paxton's funeral, we see a man the credits call "snakeman" holding a Ball Python and saying "Rosie." That's it, just a quick setup for whats to come an hour later when all of the Kentucky kin are packing up their weapons along with thermoses of coffee and sandwiches for their hunting trip in Chicago, where they end up at the aforementioned cemetary. And one of them is snakeman, who we see putting a large Boa Constrictor into a terrarium, which he also calls Rosy. (He either calls all his snakes Rosy or they though we couldn't tell the python and the boa apart.) He also wears a snake skin over one shoulder and drives a bus with a snake painted on the side with "snake pit" written on it, but nobody wants to drive with him. We find out why when we see that the bus is lined with glass terrariums full of snakes. He lets the snakes out during the cemetary battle. They're draped all over the bus unnaturally (which is typical movie set design when snakes are the props) and when one of the mobsters wanders inside, snakeman locks him inside. We see the mobster up to his ankles in a pile of snakes on the floor of the bus and we hear lots of hissing and rattling sound effects. He lets out a huge scream, and I assume we're to believe that the snakes killed him. As usual, everything in the movie could have happened, but the final scene with the snakes killing somebody. Granted, it was supposed to be funny, but it's just the usual movie lies and nonsense about the danger of snakes and their willingness to kill for no reason.
There are a few species of live snakes in the bus - garter and maybe ribbon snakes, rat snakes, green snakes, ball pythons, Burmese pythons, boa constrictors, and probably a bunch of rubber snakes, too.