Commercial artist David Drayton lives in in a lakeside house along with his wife Stephanie and five-year-old son Billy, and their home is partially destroyed one night during a particularly violent thunderstorm, described as the greatest electrical storm in recorded history. A tree smashes through the window of Drayton's room, destroying the paintings which are his work, although luckily the family had taken shelter in their basement.
The morning after, David and Stephanie witness the advance of a thick and unusual mist coming down from the mountains which then begins to spead across the lake. More immediately concerned with cleaning up in the aftermath of the storm, David and neighbor Brent Norton, along with Billy, go to the local grocery store which, like the rest of the community, was left without power. Along the way to the store, however, they see the national guard going toward the mist. While at the store, an increasing amount of police activity in the streets draws the attention of the patrons, as well as the town's civil defense siren sounding the attack signal, culminating with Dan Miller running to the store with a bloody nose warning of something dangerous in the oncoming mist. Seeing the mist roll over the parking lot and hearing the scream of a man who ventures outside, the store patrons heed Miller's advice and seal themselves within the store, which is soon shaken by violent tremors. With visibility reduced to near-zero outside and uncertainty surrounding the fate of the man heard screaming before, a siege mentality takes hold. Unable to convince anyone to escort her back home to her children whom she left alone, a mother of two departs into the mist by herself.
As confusion sets in, religious fanatic Mrs. Carmody suspects the onset of Armageddon as others search for a different answer. While trying to find a blanket for his son in the storeroom, David hears something pushing against the door of the loading dock. Unable to convince local mechanics Myron and Jim of what he witnessed, they and bag-boy Norm open the loading-bay door in an attempt to repair the ailing generator. A set of otherworldly tentacles lined with claws grip Norm, dragging him away before the loading-bay door is closed again. Now aware of the deadly properties of the mist and the danger it poses to everyone in the store, David and assistant manager Ollie Weeks (Toby Jones) try and fail to convince Norton and other skeptical patrons not to go outside. Tying a clothesline around the waist of a man who agrees to retrieve a shotgun from Cornell's car, the rest of the store's patrons are convinced when the man's severed lower body is dragged back within sight of the store.
The patrons prepare to defend themselves by making torches. New creatures appear from the mist at nightfall; enormous flying insects and pterodactyl-like animals which pluck them off of the store windows, eventually breaking one of them and allowing the creatures in. Two people die in the ensuing attack, leaving another badly burned. During the attack, one of the insects lands on Mrs. Carmody, then flies away instead of delivering a fatal sting. Viewing this as validation of her beliefs, Carmody begins quickly gaining followers among the distraught patrons in the belief that the world is ending and a human sacrifice is needed to save them from the wrath of God. After Amanda Dumfries (Laurie Holden), who has been looking after Billy, discovers a friend who committed suicide by overdose, Billy makes his father promise that he will not let the monsters catch him. Aware of the growing danger Carmody poses to the group, David turns to thoughts of escape. To test the idea of safely reaching his car, he and a group of volunteers try to retrieve medical supplies for the burn victim from the pharmacy next door, but are attacked by spider-like creatures which claim the lives of two of the volunteers. Seeing the failed expedition, Carmody's following grows stronger, with a visibly shaken Jim becoming one of her most vocal followers.
Billy, who had begged his father not to go out and leave him behind, makes him promise that from now on they will stay together. With the discovery that two soldiers from the Arrowhead Project committed suicide during the expedition's absence, the remaining soldier, Private Wayne Jessup, reveals that the project - rumored to be an attempt to look into other dimensions - was the likely origin of the mist. At Carmody's command, her enraged followers stab the young soldier several times and throw him outside, where he is quickly killed by an enormous, mantis-like creature. While preparing to leave the following morning, David and his group are stopped by Mrs. Carmody, who demands that Billy and Amanda are to be sacrificed. As the crowd advances to grab Billy and Amanda, Ollie Weeks shoots and kills Mrs. Carmody. With her followers subdued in the wake of her death, an engraged woman calls Ollie a "murderer". The group then proceeds out the front door. Ollie, Myron, and Cornell are killed in the ensuing escape and Bud Brown runs back to the store in panic, but Amanda, David, Billy, Dan and Irene make it safely to the car.
Driving through the mist, David returns home to find his wife has fallen victim to the spider-like creatures. Heartbroken, he drives the group south, witnessing the destruction left in the wake of the mist and encountering a tentacled beast towering hundreds of feet high. Eventually, they run out of gas without finding any other survivors. While Billy is sleeping, the four adults accept their fate, deciding that there is no point in going any further. With four bullets left in the gun and five people in the car, David shoots Amanda, Dan, Irene, and his son, Billy, to spare them a more violent death by the creatures. Sobbing, he attempts to shoot himself with the now-empty gun before exiting the vehicle to let the creatures in the mist take him. He hears what sounds like a creature moving toward him, but instead turns out to be a self-propelled gun, followed by a long column of other military vehicles and disembarked soldiers with NBC suits and flamethrowers. As the mist parts, several trucks filled with survivors pass David; among them the mother whom nobody from the store would escort and her two children. Realizing that he had been driving away from help the entire time, and that he had just moments ago needlessly shot dead his son and three other innocent people, David falls to his knees screaming whilst two soldiers watch in confusion.
- David Drayton - Thomas Jane
- Mrs Carmody - Marcia Gay Harden
- Amanda - Laurie Holden
- Brent Norton - Andre Braugher
- Ollie Weeks - Toby Jones
- Jim - William Sadler
- Ambrose Cornell - Buck Taylor
- Dan Miller - Jeffrey DeMunn
- Irene Reppler - Frances Sternhagen
- Billy Drayton - Nathan Gamble
- Sally - Alexa Davalos
- Norm - Chris Owen
- Private Jessup - Sam Witwer
- Bud Brown - Robert C. Treveiler
- Myron - David Jensen
- During the beginning of the movie, when the military policeman is done talking to the other soldiers, a civil defense /fire siren goes off. This is intersting because the town is supposed to be without power, so their is no way the siren could go off, unless the siren is hooked up to a backup power supply.
- The pharmacy scene is clearly based off a scene from Aliens.
- This isn't William Sadler's first time with The Mist. He played David Drayton in an audio version of the story.
- To help save time on the tight schedule, the producers and director Frank Darabont hired the camera crew from "The Shield" (2002), to shoot the film. This camera crew is able to move fast, due to the hectic TV production schedule. There was an "A" and a "B" unit, which cut down on production time.
- In the opening shot of the film, David is painting in his room. The picture he's drawing is a design from Stephen King's Dark Tower series of the gunslinger Roland. Another design in the room is that of the poster of John Carpenter's The Thing (1982). John Carpenter also wrote and directed The Fog (1980), which shares obvious themes with The Mist.
- Besides the Gunslinger illustration at the beginning of the film, The Mist shares another direct connection to the Dark Tower series of novels, written by Stephen King. This is the line "My life for you," spoken by Mrs. Carmody. This has been said by a number of villainous characters in the Dark Tower books, who had sworn allegiance to Walter o'Dim, one of the major antagonists. (Walter o'Dim made his first appearance in several earlier King novels, one the first being The Eyes of the Dragon, under the alias Randall Flagg, and the line is spoken there as well.) The Mist is one of the first short stories to refer to cross reference the Dark Tower. That same line, "My life for you," is used by Trashcan in The Stand movie as well as the book. This is also a reference made to Randall Flagg although in a different book.
- During an action scene in the film, a man runs into a wire rotating-book shelf in the grocery store. If you look carefully, you can clearly see that all the books on the shelf are written by Stephen King.
- When the group is in the next-door pharmacy, David (Thomas Jane) can be seen taking a comic book as promised for his son - an issue of "Hellboy". Later in real life, Jane directed the comicbook movie Dark Country (2009) which starred Ron Perlman, the star of the movie version of Hellboy (2004).
- Frank Darabont agreed to make the film with Dimension only under the condition that no matter what, they wouldn't change the scripted ending. They agreed.
- Director Frank Darabont originally wanted the film shown in black and white. The 2-disc DVD release contains Darabont's black and white version on the second disc.
- The pharmacy next to the Food House store is called "King's Pharmacy", most likely a reference to author Stephen King. Coincidentally, Stephen King himself once had a cameo as a pharmacist in the film adaptation of his novel Thinner (1996).
- The Dark Tower poster being worked on by David Drayton was actually painted by Drew Struzan, an artist famous for his movie posters. (Star Wars: Episode IV - A New Hope (1977), Indiana Jones franchise, Harry Potter franchise, The Thing (1982), Blade Runner (1982), etc.) All of the posters in the studio at the beginning of the film were painted by Struzan, as was the film poster for this film.
- Despite the setting in Maine, the film was shot entirely in Minden, Louisiana. To Frank Darabont's delight, Stephen King could not distinguish it from Maine when watching the film.
- Thomas Jane sat in for a better part of the editing process, since he was interested to learn about it.
- When David grabs a comic from the rack in the pharmacy, you can clearly see an issue of "The Goon" towards the bottom. Eric Powell, the creator of this comic, is shown on the special features as a friend of Frank Darabont and crew for the day.
- Director Frank Darabont wanted to cast Stephen King in a supporting role, but King turned his offer down. The role eventually went to Brian Libby.
- In the pharmacy scene, when David Drayton is collecting a comic book for his son, Frank Darabont proposed to Thomas Jane that he should grab a copy "The Punisher: War Journal" since Jane played the Punisher three years earlier. Jane declined because he had a falling out with the producers of the The Punisher (2004) franchise and decided not to return for the sequel. He instead grabs an issue of "HellBoy" as a shout out to friend Ron Perlman.
- Intially developed at Paramount.
- Shot in the six-week hiatus of "The Shield" (2002) with its cinematographer, two camera operators, their editor and the script supervisor, all of whom the director has worked with when he directed episodes of the show.
- The first film Frank Darabont has made that is set in the present, barring the opening and closing scenes in The Green Mile (1999).
- The third film Frank Darabont has adapted from Stephen King's work. The other two are The Shawshank Redemption (1994) and The Green Mile (1999).
- Frances Sternhagen's second appearance in a Stephen King film adaptation. The first was Misery (1990).
- Frank Darabont's shortest film to date.
- Shot in 37 days.
- Stephen King says that he was genuinely frightened by this adaption of his novel; Frank Darabont described that as the happiest moment of his career.
- Norm is wearing a T-Shirt from WKIT Radio in Bangor, Maine. This is one of three radio stations owned by Stephen King.
- The partially toppled highway sign towards the end of the film is an actual sign on Interstate 295 in Falmouth, Maine, on the southbound side of the highway (a little north of the Falmouth Spur).
- This is Thomas Jane's second Stephen King movie. He played Henry in Dreamcatcher (2003).
- According to Cinefex magazine, there is a favorite scene near the end of the book that was not in the script. In the scene, David Dreyton and the others with him in the vehicle, witness a giant, 6-legged behemoth walk over them. Darabont originally had excised this scene from his script. However, several of the people working with the special effects company CafeFX, convinced him to put it back into the film.
- Frank Darabont originally wrote an opening scene showing the military scientist referenced to by Private Jessup accidentally opening the dimension portal that allows the creatures and the mist to enter our world. Over dinner, Andre Braugher questioned Darabont whether this scene was necessary. After thinking about it for a week, Darabont was convinced to scrap the scene, leaving the nature of the mist more ambiguous.
- Frank Darabont's "controversial" ending actually comes directly from Stephen King's source material. Written in first-person, David entertains this notion in his mind as a distant possibility, noting there are three bullets and four people (Dan Miller doesn't make it to the car in the novella), but he ends his journal and leaves it in a restaurant the survivors have sought refuge in before the car runs out of gas. Darabont felt this ending was too ambiguous and wrote the story to its finite climax, and ending that Darabont says in the DVD commentary was endorsed by King as the ending King wished he would have thought of.
- When the hacked-off piece of tentacle is poked in the loading dock, it sizzles, turns black, and melts into a puddle of black goo. This process is exactly what happens to the bizarre creatures that appear in Stephen King's novel "From a Buick 8". Those creatures also were speculated to have come from another dimension, possibly the same one.
- Amanda has an empty six-shot revolver and two full speed-loaders in her purse. This means there are twelve rounds of ammunition for the revolver. During the course of the movie, exactly twelve rounds are fired before the revolver is out of ammunition.
- If one looks closely when Mrs. Carmody stares out into the mist and proclaims it to be death, the reflection in the store windows show the town clear of the mist.