Factual error: In the flashback where Monk is explaining how the money was stolen, the principal finds the 5 dollar bill he wrote "good luck" on and holds it up for everyone to see. The bill he holds is a 5 dollar bill which was released in 2000, with the enlarged Lincoln. The flashback takes place in 1972.
Factual error: When Monk is talking to Sherry about the painting in the art gallery where the painted woman was going to kill her husband, he says that she has a bruise on her left eye. But the bruise is actually on her right eye. While it is viewable that it is on Monk's left, he would not make that mistake.
Continuity mistake: When Cora goes upstairs, her cat is curled up asleep in a chair. In the next, close-up shot, the cat is awake and sitting at the edge of the chair cushion, looking up at Monk with its front feet hanging over the side. When the shot cuts to wide angle again, kitty is instantly back in his original position, snoozing far from the edge and curled up against the pillows. (00:32:45)
Continuity mistake: When Monk is describing the laser pointer incident to Dr. Kroger, the doctor closes his black folder and puts it on the arm of his chair. In the very next shot, it's back in his lap, and he again closes it and places it on the chair arm. (00:25:00)
Revealing mistake: In their efforts to hide Gerald's pet mouse from the hospital staff, Randy and Natalie toss the rodent back and forth and alternate hiding him in their pockets. But every time he's tossed, Devo the Mouse gains weight. In fact, Devo's (stuffed?) stunt-mouse double is at least twice Devo's actual size. (00:27:00)
Continuity mistake: When Alice is in Stottlemeyer's office and Stottlemeyer can't find Terry's present, Alice says, "But what about..." indicates the bottle of port, and then drops her arms to her sides. In the next shot (when we see Alice from the back), we can tell by the position of her elbows that her hands are not at her sides, but in front of her.
Factual error: Since Monk has OCD it would be highly unlikely for him to be on a jury. Plus, Monk works for the police department and since he technically works in the criminal justice system, that would have made him exempt from jury duty.