Character mistake: Season 3, episode 12, "Mr. Monk Gets Cabin Fever": When Randy Disher is having Chinese food in his apartment with his new girlfriend, he gets a fortune stating that he is going to get money from his uncle. Randy says that he doesn't have an uncle. In Season 5, episode 14, "Mr. Monk Visits a Farm", Randy inherits a farm from his uncle who appears to have committed suicide, but was actually murdered.
Character mistake: Julie has just passed her driver's test. At the end, she drives up with two teenage friends in the car and offers the stranded Captain Stottlemeyer a ride. Instead of simply accepting, by-the-book cop Stottlemeyer would be lecturing her. California law prohibits new teenage drivers from having other teens in the car.
Character mistake: Sharona invites Monk home for dinner. Monk is playing with his food, and Sharona guesses it is because the potatoes are mixed together with the carrots. Sharona asks Kyle to fetch two plates (So Monk can separate the potatoes and carrots.) As he tilts the dinner plate, Monk succeeds in scraping all the carrots onto one dish - save for one stray potato - all the while speaking. He completes his thought without removing the stray potato. In all other instances, Monk cannot allow such a transgression. He either corrects it before saying his piece, or after. But he cannot let it go.
Character mistake: When Monk is talking to the cops on the shooting range about the window washer's story, he says that the window washer said he was on the 7th story of the building. But in the press conference Monk saw in the bar, he said he was on the 6th story. Monk isn't likely to forget a detail like that, especially since it's the detail that's bothering him about the story.
Character mistake: The campers suspend their packs with food from a tree, while the two criminals watch from behind a tree. Criminal 1 asks, "What are they doing?" Criminal 2 responds, "They're getting their food off the ground, it keeps the bears away." But they only suspend the packs a few feet off the ground, still easily within reach of the criminals and certainly within reach of a bear.