Character mistake: You'd think prison guards on Death Row would have known a little more about safe restraints, the way they bind and gag Percy could eventually kill him. They stuff a handkerchief all the way into his mouth, then tape his mouth closed. The gag reflex could suck the handkerchief into his windpipe and suffocate him in about three or four minutes. Even if he might be able to find away around the danger of suffocation the fact remains that no trained, experienced prison guard is ever going to restrain someone in that way.
The Green Mile (1999)
1 character mistake
Directed by: Frank Darabont
Starring: Tom Hanks, James Cromwell, David Morse, Bonnie Hunt, Michael Clarke Duncan
Factual error: This movie is set in 1935. Back then, executions were done by hanging. The Louisiana Legislature changed the method from hanging to electrocution in 1940.
Paul Edgecomb: I think about all the people I've loved, now long gone. I think about my beautiful Jen, how I lost her so many years ago. And I think about all of us walking our own green mile, each in our own time. But one thought, more than any other, keeps me awake most nights: if he could make a mouse live so long, how much longer do I have? We each owe a death, there are no exceptions. Oh God, sometimes seems so long.
Trivia: In the movie John Coffey has sort of a "messiah"-like role. His initials J.C might be a reference to Jesus Christ, as this is very fitting for his role. [This is a not-so-subtle attempt which places Paul Edgecomb in the role of Pontius Pilate]
Question: When the guards are talking to Percy in the restraint room, Paul says he knows he sabotaged Del's execution. Why did he let him get away with it?
Chosen answer: Percy's aunt is married to the state Governor, giving Percy powerful connections. All it would take is one phone call from Percy and Paul and the other guards could lose their jobs and if Percy wanted to, never find jobs again. Something Paul or his friends didn't want to happen.
The characters talk about this several different times in the movies, how political connections can ruin careers.
Answer: In addition to previous answers, it is probably also worth mentioning that they will never be able to prove it. Percy mentions multiple times that he "didn't know the sponge was supposed to be wet," even when they are back in the Green Mile and only Paul and the other guards are around, indicating that it will be his defense when they ever make it into a thing, knowing that they will never be able to prove otherwise.
Suggested correction: Not everyone even has a gag reflex, and it is easy, though not comfortable to push the handkerchief forward into the mouth with the tongue. You can see Percy breathing through his nose, so he's not running out of air. The other guards had no intention of leaving him in the cell for a long time, only long enough to teach him a lesson.
It doesn't matter what he "might" be able to do, or even if he could push the handkerchief forward. That's not the mistake. A trained, experienced prison guard would not restrain someone like that. Never.
Again, what might or might not have happened is irrelevant. No skilled, trained, experienced prison guard would apply a gag in this way.