Continuity mistake: When Annie shows Paul her gun, she says "I might put bullets in it," then leaves the room. It's pouring with rain, but when Annie steps out the front door, you can see her hair is already wet before being outside.
Continuity mistake: After Annie tells Paul she knows about his superstitions and that there is only one manuscript, when Annie holds the single match and box of Diamond matches, which have a distinctive blue and red top, the matchbox faces the opposite way between the shot facing Paul and the next shot facing Annie. (00:36:05)
Continuity mistake: When Buster flies over Annie's house, there's a shot of the house from outside and the roof is covered in snow. The shot from the helicopter, the amount of snow changes, including a couple sections being nearly void of snow. There are also a lot of extra tire tracks. (00:38:00)
Continuity mistake: When Annie lifts Paul off the floor and lays him back into the bed, there is initially no tape over the brace on Paul's left knee. In the next shot, which is somewhat bird's eye view, there are three pieces of white tape over the brace, then there are none again when she finishes lying him down.
Continuity mistake: During the rainstorm, it shows snow on the roof of the house. The next shot of the rainstorm still has the same amount of snow on the roof - some should have been washed away.
Continuity mistake: When the sheriff looks at the last newspaper article about Annie, the caption reads "There is a higher justice than that of man..." Then when it zooms in on the caption it is switched to "There is a justice higher than that of man..." (The 2nd one matches the Misery book quote). (01:25:00)
Continuity mistake: When Paul complains that the paper smudges, Paul types seven letters on a piece of paper to prove it. In the next scene, we see the word he typed was "smudge" which only has six letters.
Continuity mistake: Shots of the roof show two different amounts of snow and it alternates between the two for the whole movie.