Mr. Monk Gets Married - S2-E15
Factual error: Disher gets the armoire open and recoils from the smell of the dead body inside, despite it being wrapped in plastic. But he somehow didn't smell it before getting the door open, despite it providing hardly any protection from a smell like that.
Mr. Monk Falls In Love - S7-E6
Plot hole: It is not realistic that Miss Zladovic is confronted with the murder weapon for the first time in her flat after she had been arrested and interrogated about the same exact murder days before. It is also impossible that the police did not show her a picture of the murder victim as it is police standard to ask any suspects for connections/relations to "their" victim.
Mr. Monk Takes His Medicine - S3-E9
Factual error: The medication Monk is given is called Doxinyl, which is a real medication, but it's an antibiotic, nothing to do with OCD and certainly wouldn't cause the side effects shown.
Mr. Monk and the Daredevil - S6-E7
Continuity mistake: During the fight with Harold's cousin Natalie's shoes are on and off her feet several times.
Mr. Monk and the 12th Man - S2-E9
Plot hole: Monk identifies the killer because of a shirt sleeve that gets ripped off... he noticed the button is sewed on in a unique manner with the threads parallel as opposed to the "standardized" crisscross pattern. The killer and Monk coincidentally use the same dry cleaner and Mrs. Ling sews buttons parallel because it's her style. Dialogue in the episode indicated she is the only one who sews buttons on like that. But I checked over 20 button up shirts here at my house and the ratio of crisscross to parallel button sewing methods is 50% of each - hardly some unique identification method.
Mr. Monk and the Panic Room - S3-E2
Factual error: The cops gain entry to the panic room to be faced with a chimp waving around a loaded handgun, apparently having shot a man, and shrug and make jokes about reading him his rights, instead of expressing the slightest concern that this animal might shoot them. Cops shoot remotely aggressive dogs all the time, but an ape with a gun doesn't even make them raise an eyebrow. Plus the police never did a gunshot residue test on the chimp. Standard procedure, and would've proven they didn't shoot.
Mr. Monk and the Wrong Man - S6-E8
Plot hole: Monk supposedly hears for the first time that Max was not carrying anything away from the crime scene when he speaks to the witness in front of the church. This leads him to conclude that there must have been a 2nd man with Max 14 years ago. But this does not make sense given that the witness with her photographic memory did not change her testimony and given Monks ability to observe and memorize details it is very unlikely that he did not come to that conclusion 14 years ago already. (00:32:45)
Plot hole: In this episode the police are using the toupee of the commissioner to identify the torso as the missing woman. In reality that would not be possible since cut hair is missing the root and therefore only contains mitochondrial DNA, which can only be used to identify a human's relation via the female lineage, as it is the same in relatives and passed through generations from the mother to her children. Furthermore, the identification of said torso would likely not be sufficient proof that Mr. Harley killed her as he may claim that somebody misled him to believe she was in Paris by placing the telephone call he mentioned to police.
Other mistake: Mr. Monk is solving his 100th case, but in Season one Episode 3 Julie gives him 100 trophies, saying they rounded down from 104 to make an even number.
Mr. Monk and the Other Woman - S1-E8
Plot hole: Monk's led to the killer because he figures out that he "added a file" to the lawyer's filing cabinet, judging by the left/middle/right tabs being off. But this makes no sense on two levels - firstly why would he need to add a file? He was just replacing the real will with a forgery. He just took the old one out and added the new one, he didn't need to mess with the filing system at all. Secondly, he picks that one out because the tabs are offset, but what if the lawyer had just taken on a new client or added other paperwork? Then the tabs would be off too, but that never seems to be considered.
Mr. Monk and the Man Who Shot Santa - S6-E10
Other mistake: When the star of Bethlehem is stolen, the shots are reused from episode 4-13, with a flail used to breach the glass case, which isn't present in this episode.
Mr. Monk and the Other Woman - S1-E8
Audio problem: When Monk finally turns around at the funeral to tell the old man behind him to be quiet, you can still hear the man coughing. But the man's face is still, and his mouth is not open, and he isn't making the sound.
Mr. Monk and the Buried Treasure - S6-E6
Continuity mistake: In the captain's office, Randy is holding his cup with both hands and he states that he has a Motorola phone in his pocket. He begins to turn to his left to expose his suit pocket jacket. In the very next shot, which is a wide angle of everyone, he is beginning his turn again so Natalie can retrieve the cell phone.
Mr. Monk and the Buried Treasure - S6-E6
Continuity mistake: At the end of the episode, when Dr. Kramer and Monk are talking, Dr. Kramer is hunched over listening to Monk. In the very next camera shot, with the camera pointing at Dr. Kramer, he is sitting straight up and just finishes crossing his arms. A couple of seconds later, it switches back to Monk and you can see Dr. Kramer hunched over again and arms uncrossed.
Mr. Monk and the Very, Very Old Man - S2-E5
Continuity mistake: When Stottlemeyer moves the snake, the pinecone falls on the ground. The next scene, where Monk is on the table and talks to Stottlemeyer, the pinecone is back on the shelf. (00:25:26 - 00:26:36)
Mr. Monk Takes Manhattan - S3-E1
Deliberate mistake: After Monk and Sharona speak to Gratnik in Dumbo, they take the subway back to Manhattan. While Monk is sobbing, in the first exterior shot the "A" train slows into the 42 St station in Manhattan; note the "A" at the left with the driver on the right, as well as the "42" station sign not reflected backwards, all revealing a flipped shot. Then it's the "C" train when it stops, with Monk and Sharona back in Brooklyn, even further now at the "Hoyt-Schermerhorn Street" platform (used for TV shows and films), in lower Downtown Brooklyn. (00:21:55)
Mr. Monk Takes Manhattan - S3-E1
Visible crew/equipment: After Stottlemeyer swipes the keys to Captain Cage's office, when he and Disher enter Cage's office the reflections of the moving boom pole and camera operator beside the camera are visible on the glass window. (00:20:45)
Mr. Monk Meets His Dad - S5-E9
Visible crew/equipment: When Monk and his dad pull over to a diner there are visible feet behind the truck.
Mr. Monk and the Red Herring - S3-E10
Visible crew/equipment: At the science fair during the fire, a kid offers use of his fire extinguisher. When the captain goes to take it from him you can see a member of the crew handing it to him.
Continuity mistake: When Natalie arrives at the marina she is wearing a long trench coat but after she discovers the dead body in the water she is wearing a short one.