In a small town in Upstate New York named "Sam Dent", a school bus skids into a lake, killing 14 children. Their grieving parents are approached by a lawyer, Mitchell Stephens (Ian Holm), who is haunted by his dysfunctional relationship with his drug-addict daughter. Stephens persuades the reluctant parents to file a class action lawsuit against the state, school district, or other entity for damages, arguing that the accident is a result of negligence.
As the Earth passes through the tail of a comet, previously inanimate objects (ranging from weapons to electric signs to electronics to vehicles to lawnmowers to an electric knife) start to show a murderous life of their own. In a pre-title scene, a man (King in a cameo) tries to withdraw money from an ATM, but it instead calls him an "asshole", and he whines to his wife (King's real life wife Tabitha). Chaos soon begins as machines of all kinds come to life and begin assaulting humans: a drawbridge inexplicably raises during heavy traffic, resulting in multiple accidents, most notably the black AC/DC van and a watermelon truck; while at a Little League game, a vending machine kills the coach by firing canned soda point-blank into his groin and then to his skull; a driverless steamroller flattens one of the fleeing children.
As is the case with the two preceding Smokey and the Bandit films, Smokey and the Bandit Part 3 begins with Big Enos (Pat McCormick) and Little Enos (Paul Williams) offering a sizable wager on one's ability to transport a shipment a large distance in a short period of time. Offering a slight twist, however, the offer is this time made to a retiring Sheriff Buford T. Justice (Jackie Gleason), betting $250,000 against his badge on his ability to transport a large stuffed fish from an eatery in Florida to Texas.
Dyan Cannon plays Madie Levrington, a wealthy woman who is also neurotic. She was committed to a New York mental institution by her husband, Benjamin, in order to keep her from divorcing him and taking his money. She manages to escape and, in the process, hitches a ride on a livestock truck.
At a corporation's base on the Neptunian moon Triton, mercenaries are setting up a defense perimeter to try to hold off an unstoppable cyborg warrior. The commander, Nabel, seals himself inside the control room. The cyborg destroys the soldiers' tank and then attacks a helicopter—which crashes into the control room. The soldiers are killed one by one, until Nabel finally deactivates the cyborg with a remote control. The remaining corporate employees discover that the cyborg was created by company owner E.J. Saggs. Saggs arrives at the base just as the battle ends, and takes the remote from Nabel. He reactivates the cyborg and orders it to kill Nabel.
Brothers Joe (George Raft) and Paul Fabrini (Humphrey Bogart) are independent truck drivers who make a meager living transporting goods. Joe convinces Paul to start their own small, one-truck business, staying one step ahead of loan shark Farnsworth (an uncredited Charles Halton), who is trying to repossess their truck.
The film opens on truck driver Patrick Quid (Stacy Keach) as he pulls into a motel for the night. Quid notices a man in a green van checking in with a female hitchhiker he had passed earlier because the trucking company policy forbids it. Nevertheless, Quid is miffed at the man for taking the last room in the motel and picking up the attractive hitcher. In the motel, the hitcher strums a guitar naked on the bed, while the unidentified man unpacks a new guitar string. He winds the string around his gloved hands and uses it to strangle the woman.
At a loading dock in Cleveland, Ohio in 1937, supervisor Mr. Gant welcomes a new worker, Lincoln Dombrowsky (Frank McRae). Gant tells him the job requirements and pay rules. He'll be paid for working 8 hours and if he has to work overtime, he still gets paid only for 8 hours. If he drops any of the merchandise, the cost comes directly out of his pay. These are examples of unfair working practices faced by the laborers. Later Dombrowsky drops a few carts of tomatoes, which is taken out of his pay; another worker is fired for helping him collect the fallen merchandise. Johnny Kovak (Sylvester Stallone), another worker resentful of mistreatment, leads a riot. Afterward, the workers go to the office of Boss Andrews. Kovak believes he negotiates a deal for the workers, but the next day he and his friend Abe Belkin (David Huffman) are told they are fired.
Frenchmen Mario and Jo, Dutchman Bimba and Italian Luigi are stuck in the isolated Southern Mexican town of Las Piedras. Surrounded by desert, the town is linked to the outside world only by a small airport, but the airfare is beyond the means of the men. There is little opportunity for employment aside from the American corporation that dominates the town, Southern Oil Company (SOC), which operates the nearby oil fields and owns a walled compound within the town. SOC is suspected of unethical practices such as exploiting local workers and taking the law into its own hands, but the townspeople's dependence upon it is such that they suffer in silence.
Vic Brennan is a sailor from Dublin who decides to use his family's fortune and move to Africa to open a truck-hauling business. He is accompanied by his wife, Marie, and a meek cousin, Samuel, who loses their documents, causing customs agents to seize some of their cargo.
John W. "Jack" Burns (Kirk Douglas) works as a roaming ranch hand much as the cowboys of the old West did, refusing to join modern society. He rejects much of modern technology, not even carrying any identification such as a driver's license or draft card. He can't provide an address because he just sleeps wherever he finds a place.
Dans un endroit du sud marocain et du Sahara espagnol à l'approche des années 1960, Castagliano qui est un patron aux méthodes douteuses et surnommé « la Betterave » à cause de son diabète, dirige d'une main de fer une entreprise de transport routier dont il exploite les employés. Il engage John Steiner, un routier « mexicain » soi-disant né à Saltillo pour conduire sur 2 000 km vers le sud un véhicule articulé Berliet rouge flambant neuf, affrété d'un mystérieux chargement d'une valeur déclarée de 100 000 dollars, direction Moussorah. Pendant une conversation téléphonique entre Castagliano et son client, on apprend qu'il a engagé Steiner la veille pour qu'il en sache le moins possible sur ce camion.
Au cours de la guerre d'Algérie, quatre hommes et deux femmes acceptent de convoyer pour le compte du Front de libération nationale algérien des camions à travers le désert.