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.
The Dark Tower poster being worked on by David Drayton was actually painted by Drew Struzan, an artist famous for his movie posters of Star Wars franchise, 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.
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, a Clint Eastwood-like character living in a Middle-Earth-like world. Another design in the room is that of the poster of John Carpenter's The Thing (1982). Carpenter also wrote and directed The Fog (1980), which shares obvious themes with The Mist, as well as Christine (1983), an adaptation of a Stephen King novel.
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).
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 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.
The line, "My life for you", spoken by Mrs. Carmody in the film, is a recurring line in other Stephen King texts, spoken by villainous characters to Randall Flagg (alias Walter O'Dim, Marten Broadcloak, etc.), the super-powered master of evil in several King stories.
Frank Darabont had originally been offered $30 million by a producer to make this film, but with one crippling caveat: Darabont would have to change his planned ending, a conclusion he'd personally envisioned and nursed for twenty years. In the end, he turned to producer Bob Weinstein and made the movie for half the amount, but only after forfeiting his directorial salary.
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 original Stephen King novel was also the inspiration for the video game Half-Life (1998), where scientist at a top secret military base are running experiments with inter-dimensional portals and open the flood gates to its hostile inhabitants.
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.
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).
Actor Sam Witwer plays the role of Private Jessup in the film. Singer/actor Sheb Wooley, whom by many is said to be the voice behind the Wilhelm scream, played a role with the same name and rank in the movie Distant Drums (1951), which is the first movie that features the Wilhelm scream.
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.
At the end of the film, when the rescue truck with Melissa McBride passes by David, Frank Darabont originally wanted a second truck to pass by David. This one would have been filled with various people from the market, including Jim, Bud, Mr. Mackey, and most of Mrs. Carmody's ex-followers, indicating that they were rescued safely from the store and making David realize that he and his group should have never have even left the market in the first place. Unfortunately, most of the extras and other actors had already left because their parts were finished, so Darabont had to scrap this idea.
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.
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.
According to Cinefex magazine, Frank Darabont did not originally plan to include the giant, 6-legged behemoth which walks over the car, even though this is one of the novella's most popular scenes. Several CafeFX special effects technicians convinced him to put it in the film.
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.
Originally, David and his group, while driving away from the market, were supposed to drive by the webbed, desiccated body of the Woman With Kids at Home. However, Melissa McBride's acting during the scene where she leaves the market was praised so much that it was decided to not only have her character survive, but bring her back at the end completely unscathed and with her children.