Mr. Monk and Little Monk - S4-E8
Continuity mistake: When Monk is doing the summation for the present-day case with Sherry's ex-husband sitting in the chair, at first you can see that the painting is directly behind him. However, shortly thereafter during the summation, the painting has somehow shifted to the viewer's left and is no longer directly behind him. While it's plausible that someone could have moved the painting, it's just not believable since less than a minute has passed. Besides, would Lt. Disher (he was closest) really take it upon himself to move evidence?
Mr. Monk and the Secret Santa - S4-E9
Continuity mistake: In the beginning scene it shows someone injecting a liquid, with ease, into what appears to be a corked wine bottle. Then around the 13-min mark you see the Captain re-gift the bottle and when the person opens it, it's a pull cork with a hard top, something a needle would not easily go through. (00:00:10 - 00:13:23)
Mr. Monk and the Secret Santa - S4-E9
Continuity mistake: When Alice confesses to the murder in her kitchen, a large green plastic bowl that's been sitting on the counter disappears between shots. (00:38:05)
Mr. Monk and the Secret Santa - S4-E9
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.
Mr. Monk Goes to a Fashion Show - S4-E10
Revealing mistake: The fan letter Monk wrote to shirt Inspector 8, shown in close-up where it hangs on her work station wall, consists of the same paragraph printed out twice. (00:06:45)
Mr. Monk Goes to a Fashion Show - S4-E10
Continuity mistake: When the fashion designer draws a sketch on the newly painted wall, the drawing changes between shots, from four lines to about seven.
Mr. Monk Bumps His Head - S4-E11
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)
Mr. Monk Bumps His Head - S4-E11
Other mistake: The diner Monk enters to eat something after the truck driver gave him five bucks is the same diner that Christie and Sharona are waiting in to meet Monk after work in the episode Monk and the employee of the month. But while this episode is said to be in Wymington, the earlier one is set in San Francisco.
Suggested correction: This is trivia at best. While the set may be reused, it's not meant to be the same diner. It might be a chain restaurant so they look similar, but the seats inside are different.
Mr. Monk and the Captain's Marriage - S4-E12
Continuity mistake: When Stottlemeyer goes to open the window in his house, the position of his body (especially his right arm) changes between shots. (00:07:50)
Mr. Monk and the Captain's Marriage - S4-E12
Continuity mistake: In the hospital scene, the items on Gerald's tray change positions several times between takes. (00:27:00)
Mr. Monk and the Captain's Marriage - S4-E12
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)
Mr. Monk and the Captain's Marriage - S4-E12
Continuity mistake: While at the crime scene in the junkyard, Monk is trying to explain things, but is unable to concentrate because one of the stacked junked cars still has a headlight in it. Frustrated, the Captain shoots the light out so Monk can continue, but as the screen pulls back the headlight is still unbroken in the car.
Mr. Monk and the Big Reward - S4-E13
Continuity mistake: During grocery checkout, the vegetable oil keeps shifting around between shots, from next to the clerk to behind the cereal. (00:06:00 - 00:07:00)
Mr. Monk and the Astronaut - S4-E14
Audio problem: When the astronaut is speaking and we hear "I made a mistake, Captain. Five years ago," his lips don't match what we hear him saying. (00:11:10)
Mr. Monk and the Astronaut - S4-E14
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)
Mr. Monk and the Astronaut - S4-E14
Plot hole: The murderer mails a garage door opener with the button taped down to his victim and kills her by remote. But A) With the switch continuously in the "on" position, the battery would die long before the package arrived, and B) Door openers use special frequency tones that are set much like a safe combination. The likelihood of one control opening 3 different doors in the same area, as it does here, is virtually nil. (00:33:30)
Mr. Monk and the Astronaut - S4-E14
Plot hole: There is no drug in the world that could render a healthy adult unconscious for two days with a single dose, but let's go with the dramatic licence and allow that there is. Any such drug would be instantly detectable in any one of a dozen toxin screens carried out during an autopsy, and isn't someone going to wonder how a comatose woman hanged herself?
Mr. Monk and the Astronaut - S4-E14
Plot hole: The whole plot hinges on Steve Wagner knocking the victim out for 2 days, remotely hanging her while he's in space, then removing the hanging machine when he lands. But keeping someone unconscious chemically for 2 DAYS is a hell of a feat. And unpleasant though it is, she'd be voiding her bowels over those 2 days, leaving a serious mess, plus all the chemicals necessary to keep her unconscious would be found in an autopsy.
Mr. Monk and the Astronaut - S4-E14
Continuity mistake: When the captain receives the victim's phone record (outside at the neighbor's house) he calls a number on the bill. But the phone starts to ring (on the other end) before he presses the last digit.
Mr. Monk and the Astronaut - S4-E14
Factual error: During their examination of the crime scene, neither Monk, Stottlemyer, Sherona, Randy or anyone else in the room wear gloves or any kind of other protective clothing. They handle artefacts that could be critical to an investigation of the woman's death, including a cheque made out to her, and they hopelessly contaminate them by doing so.