Mr. Monk and the Billionaire Mugger - S1-E7
Continuity mistake: When Stottlemeyer pulls his gun on Mr. Modine, the safety is off and the gun is cocked, but in the next shot it's not cocked and the safety is on. Then we see the safety off, but not cocked.
Mr. Monk and the Other Woman - S1-E8
Plot hole: Monk says that the two files, both with tab at the middle, were kept together, which led him to discover that the person related to this file is 'the guy'. In an earlier scene, when Monk is searching the file cabinets, he picks up one of these two files and tells Sharona that this file is of 'the guy'. How can he say which one of the two files with middle tabs, which are put together, is related to 'the guy'? Impossible. (00:39:00 - 00:40:00)
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 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 Takes a Vacation - S1-E10
Continuity mistake: When Sharona is having dinner at the restaurant and asks her date, "Have you ever been married?", she puts down her drink and lets go of it. When the shot changes she is putting the glass down again and holding on. In the third shot her arms are folded.
Mr. Monk Takes a Vacation - S1-E10
Continuity mistake: When Monk is talking to Benjy, he buttons up the top two buttons on his shirt, but in the next shot of him they're undone, and he's re-buttoning them.
Mr. Monk and the Earthquake - S1-E11
Continuity mistake: After the quake, all but one of the art pieces have fallen out of the Rutherford's display case and lie shattered on the floor. But seconds later, when Christine pushes the cabinet over, most of the broken items have vanished from the floor. (00:02:30)
Mr. Monk and the Earthquake - S1-E11
Audio problem: Sharona and Benjy are forbidden access to their damaged apartment building. The policeman tells them to call a certain emergency number, but when he says this, his lips aren't moving. (00:11:00)
Mr. Monk and the Earthquake - S1-E11
Continuity mistake: Sharona tells her sister that Monk needs the guest room because he "doesn't sleep on couches," but in "Mr. Monk and the Marathon Man," she had to stop him from taking a nap on the victim's couch. (00:15:15)
Mr. Monk and the Earthquake - S1-E11
Continuity mistake: When Sharona and her sister are talking on the couch, her sister is playing with her hair when she asks "Are you in love with anybody?" The shot changes to Sharona answering from over her sister's shoulder and her sister's hand is in a fist and pressed against her head. (00:16:00)
Mr. Monk and the Red-Headed Stranger - S1-E12
Revealing mistake: In the scene where a man is streaking, he is carefully made to look naked. But when he is running through the park, there is one shot where you can see some black underwear.
Mr. Monk and the Red-Headed Stranger - S1-E12
Continuity mistake: In the closing scene with Willie Nelson, there are a few times when the clarinet music changes notes, yet Monk's fingers do not move. There is also one point where Monk takes a breath mid-note.
Mr. Monk and the Red-Headed Stranger - S1-E12
Continuity mistake: In the scene where Willie Nelson is rehearsing, his pigtails change position depending on the shot.
Mr. Monk and the Red-Headed Stranger - S1-E12
Continuity mistake: Before meeting Willie Nelson on his tour bus, Monk is outside the radio station. When a car comes past the shot shows from inside the car and we see Monk putting his right hand up to his forehead and touching it. In the next shot his hand is now further down his face and is not touching it anymore.
Mr. Monk and the Red-Headed Stranger - S1-E12
Plot hole: When Monk explains to Miss. Mass how she had murdered Sonny, a flashback of the crime shows that she isn't wearing gloves when she leaves the note to get him to go to the alley. Had the cops checked the note for prints, they would have shown Miss. Mass' fingerprints on it and knew she was responsible for Sonny's death.
Suggested correction: Just because they lifted fingerprints off the note, there wouldn't be a way to identify them as belonging to Ms. Maas if her prints aren't in the system. As a witness (and ruled out as a suspect because they thought she was blind), they wouldn't have fingerprinted her just because the found unknown prints and wanted to rule her out.
What about gun residue on the hands?
Mr. Monk and the Airplane - S1-E13
Continuity mistake: "Nationwide Airways" is the name of the fictional carrier used in the episode, and it even has its own logo and livery. Yet in the exterior shot of the plane pushing back from the gate, it has suddenly transformed itself into a Delta Air Lines plane. It also looks like a 1990s Delta plane while it is taking off. (00:13:05 - 00:15:00)
Mr. Monk and the Airplane - S1-E13
Factual error: Though anti-freeze is lethal it does not kill quietly and fast but rather agonizingly, painfully and slowly, inducing vomiting and fever. (00:30:30)
Mr. Monk and the Airplane - S1-E13
Factual error: When the flight attendant announces that "they have been asked to return to the gate" the French pilot and his mistress are already celebrating with a glass of wine, but that is impossible since drinks are only served after the take off phase when the plane has reached its traveling altitude. (00:41:15)
Mr. Monk Goes Back to School - S2-E1
Character mistake: When Kathy is presenting her model of General Robert E. Lee's surrender to General Ulysses S. Grant on April 9th, 1865, she incorrectly states that the surrender occurred "at the courthouse in Appomattox, Virginia." The surrender didn't take place at the actual courthouse, but rather at the McLean House, a private residence selected by Grant and his aides for the meeting of two of the greatest generals in American history. This is a common misconception as the village itself is called Appomattox Courthouse. (00:29:05)
Mr. Monk Goes Back to School - S2-E1
Continuity mistake: When Monk is leaving Derek Philby's classroom, he is quite content to just pick up a piece of chalk (with his bare hands) to write on the blackboard, but earlier, he makes sure to use a chalk holder to do this and nearly has a panic attack when he gets chalk dust on himself.
