(at around 2h) Wild Bill shown laying on a mattress on the floor, after he tore up his cell, from which he gets up to request a drink of soda. After he is given the soda, he sits down on his bed which has a mattress. Shortly thereafter, he is again shown passing out on his bed.
(at around 59 mins) When the guards are trying to subdue Wild Bill, he hits Guard Harry with the back of his head, knocking him to the ground. For a brief but clearly visible moment, Percy is seen behind him, on the left side of the room. But before that and throughout the rest of the scene, he's on the far right side, frozen with fear.
(at around 33 mins) The crumb from the cheese wafer that the guards feed to Mr. Jingles is lying on the floor after Percy throws his baton at it and is still on the floor when he starts chasing Mr. Jingles with a waste basket but is gone in the next shot when Percy throws the waste basket at the mouse.
The sex of the mouse changes. When Mr. Jingles first appears, and then scuttles under the door way - the mouse is clearly male (distinguishing between the sexes of mice is easy because of the size of the genitals). However during the scene where John Coffey shares his cornbread Mr. Jingles is clearly a female mouse.
(at around 2h) When Percy is sitting at his desk reading a book on mental patients with the dirty magazine in it, Brutal and Paul come in and Percy jumps up closing the book and throwing it where it falls off the edge of the table. In the next shot when Paul picks up the book it is laying on the table opened to the page where the magazine is.
The movie shows mixed black and white prisoners both in the prison population and on the chain gang. In the 1930s this would not have happened.
In the execution scenes, the victims of Old Sparky convulse as if in a severe seizure as the electricity is rolled through them, however, in real life, this would not and does not happen. The constant flow of electricity causes all of the victim's muscles in his/her body to contract until the electricity is stopped. Additionally, the kind of screaming heard would be impossible because of this, as the screaming heard is the kind made with a fully opened mouth, not a neutrally positioned jaw that would come as a result of the contraction of both the jaw opening and closing muscles produced by the electricity.
Executions were carried out at local courthouses in Louisiana until 1957, when they were moved to a state prison.
During prison scenes the guards are wearing sidearms. Real prison guards would not wear sidearms in the prison population for fear that one of the inmates might grab it and hold the guard hostage or kill the guard.
When Percy shoots wild Bill, there were 7 shots. A standard revolver only holds 6 rounds.
(at around 1 min) You can see a smallpox vaccination scar on the upper arm of the murdered girls' father in the opening sequence of him running through the field. Vaccination was widespread in the USA by 1935, the time of the movie.
(at around 1h 45 mins) After the execution, Brutus hands Percy an old Soda Acid fire extinguisher. The extinguisher is being held horizontally. The old style soda acid type extinguishers would automatically begin discharging the agent if the extinguisher was turned over onto its side, or turned upside down.
(at around 1h 18 mins) While subduing Wild Bill, he took off a leather belt to fight the 2 guards. No prison would allow a belt.
The homes shown in the film are fairly large for men working a state government job in the 1930s. While the warden's home would likely be a benefit from working at the prison, the rest of the homes were much larger than homes that would be owned today by people earning far larger amounts of money working for the prison system.
When John has just been put in his cell, Paul asks him if he can spell, John explains about his last name, and starts to spell "K-o" before Paul stops him. Yet every time you see his name written after that, it is always "Coffey".
The movie, set in 1935, depicts executions in Louisiana being carried out by electrocution, but the Louisiana Legislature did not change the method of execution from hanging to electrocution until 1940.
(at around 1h 14 mins) The film is set in 1935 but Eduard Delacroix is reading a November 1937 issue of "Weird Tales".
On his office wall, Warden Hal Moores has a portrait of Franklin D. Roosevelt, who in 1935 was the President of the United States. However, the portrait on the wall is Roosevelt's official White House portrait, which was painted by artist Frank O. Salisbury in 1947, two years after Roosevelt's death.
(at around 2h 5 mins) Although Scotch tape was invented in the 1930s, it had a yellowish tint and would never have been used over a person's mouth. It did not have the adhesion of modern-day packing tape and would immediately come off from saliva. Rather, they would have used white cloth adhesive bandages that came on a metal spool that fit in a steel sleeve. Even early Johnson & Johnson Band-Aids were cloth with a sticky, white adhesive that would remain when removed. Clear packing tape was not widely introduced until the 1980s. Even the packing tape used in the 1970s, made of the same plastic, was brown.
(at around 1h 6 mins) In 1935, Jan asks Paul what the doctor said. Paul replies, "Oh, you know doctors - gobbledygook mostly." The word "gobbledygook" was coined by U.S. Rep. Maury Maverick in 1944.
When John Coffey says "If she don't mind" when asked what he wants for his last meal, his jaw and lips do not move.
(at around 1h 2 mins) When Paul Edgecomb approaches John Coffey's cell after getting kicked in the groin, John Coffey asks him to come closer to the bars. When Eduard Delacroix warns Paul that he's not supposed to do that, Paul replies, "Mind your business, Del." But if you watch Tom Hanks' lips, he actually says "Mind your own business, Del."
In the scene where William Wharton is attacking the guards when first being brought into death row, we clearly hear the sound of Brutal whacking Wild Bill over the head just before he actually hits him.
(at around 2h 10 mins) In the dolly shot up to John Coffey just as the truck pulls up to the Warden's house, crew members are momentarily visible in the reflection of the rear window.
(at around 2h 30 mins) Mrs Detterick calls Klaus "Ralph" in the flashback scene when he is on the barn roof.
(at around 13 mins) As Percy leads John Coffey into E Block, he continues to announce, "Dead man walking!" The phrase "Dead man walking" is usually announced to other nearby inmates and staff that a condemned inmate is being lead to their execution.