Character mistake: When Randy Disher is having Chinese food in his apartment with his new girlfriend in 3-12 "Mr. Monk Gets Cabin Fever", he gets a fortune stating that he is going to get money from his uncle, and says that he doesn't have an uncle. In this episode Randy inherits a farm from his uncle who appears to have committed suicide, but was actually murdered.
Continuity mistake: The edition of the San Francisco Chronicle with the headline on Jimmy Cusack's death is dated April 1, 2006. However, at the end of the episode, which is a few days later, the newspaper with the front page photo of Stottlemeyer arresting Ron Neely, is dated March 24, 2006. In addition to the fact that the date of the arrest is a full week before the date of the murder, April 1, 2006 fell on a Saturday, when the episode says the murder was on a Monday night. (00:05:05 - 00:40:25)
Revealing mistake: Look at the stuntman who stands in for Tony Shalhoub when the balloon crashes and the basket scrapes and bumps along the ground. He is about fifty pounds lighter than Shalhoub, looks nothing at all like him and his hair looks like a Harpo Marx fright wig dyed black.
Factual error: The FBI agent runs a computer check and prints out a list of all the pet stores in San Francisco selling ferrets. But he shouldn't have been able to generate any list at all. Pet ferrets are illegal in the state of California, and are not sold in pet stores there. (00:15:00)
Plot hole: Monk's dad, Jack, drives an 18 wheeler. In the scene where Jack pulls over to the side of the mountain road so they can discuss specifics about the GPS, a brake line is shown breaking and spurting what I assume is meant to be brake fluid. The rig then rolls down the mountain. However, 18 wheelers don't have brake fluid since they don't have hydraulic brakes, they have air brakes. Even if the rig lost its brakes due to loss of air pressure, the brakes are spring loaded to lock up all the wheels in this case and prevent movement. That's how you set the parking brakes, by releasing the air pressure. In other words, if he has air, he can use his application brakes; if he's lost air, he has his parking brakes set. Rigs that lose their brakes going down steep grades do so due to extreme overheating, causing brake fade, an inability of the brake shoes to grab the brake drums. This wouldn't have happened while they were parked.
Factual error: While Monk and Natalie are waiting for the mayor to exit City Hall with his aide, you can see a cable car turning around the corner behind them. San Francisco City Hall is located on Van Ness Avenue between Grove and McAllister Streets, and this is at least six blocks from the nearest cable car line (which would be the turntable at Powell and Market Streets). (00:20:00 - 00:26:05)
Deliberate mistake: In the opening scene, Wood's tie is grabbed by an exposed fan belt located above the side of the engine. However, this belt/pulley assembly doesn't exist in a real truck's engine compartment - the fan belts are all in front of the engine, where the camera can't see them easily. The prop master must have added this dangerous device to the truck to allow the camera to see the strangulation.
Continuity mistake: Natalie carries a large box full of house plants into Monk's kitchen and starts placing them one by one on the counter while he answers the phone. Each time the shot changes, a large red flower switches itself from the left side of one plant to the right side and back again, and sometimes disappears altogether. (00:09:00)
Continuity mistake: Randy is desperately trying to pry his teenage acne photo off the doctor's wall. He knocks the photo underneath it crooked, but it rights itself in the next shot. Then he pulls his picture free, making a large hole in the wall, but knocks all the surrounding photos off onto the floor. There's no time lapse, but when he turns around, the fallen photos have all put themselves neatly back up on the wall, and the hole is gone. (00:32:30)
Continuity mistake: When Monk, the Captain and Disher talk to Dr. Scott during his cardio test, the doctor's hospital gown is falling off his left shoulder in about half the shots, but is pulled up to his neck in the rest. This alternates several times throughout the scene, though he never touches or adjusts the gown. (00:19:30 - 00:21:30)
Continuity mistake: When Kris Kedder is on stage performing "Peggy's Gone to Memphis," notice that his 12-string guitar keeps changing positions between shots. In most of the long shots, he's holding and playing it. In most of the closer angles, it's hanging at his side and he's holding the microphone instead. (00:30:15)
Continuity mistake: Just after the touch football game with Kyle, Monk tells Natalie, "He missed that ball on purpose. He dropped his hands." But Kyle didn't drop them: he kept his hands up and deliberately missed the ball. Monk, who always notices every tiny detail, wouldn't make such a mistake. (00:32:20)
Continuity mistake: Monk uses paper towels to grab the phone, dragging a length of white paper across the kitchen counter and leaving it there. But when he turns around to talk to Natalie, the counter behind him is bare. The paper towel trail has vanished. (00:05:40)