The show intro shows Monk pouring boiling water on a toothbrush. The toothbrush is a normal toothbrush with a rectangular head. He then immediately brushes his teeth with a oval shaped multicolored toothbrush.
Continuity between episodes:
- The mayor in Mr. Monk and the Very, Very Old Man (2003)(#2.5) (Jim Jansen) is not the same mayor in Mr. Monk and the Garbage Strike (2006)(#5.2) (Chi McBride). Although there could have been an election between episodes.
- In Mr. Monk Goes to the Ballgame (2003)(#2.3) Monk tells Dr Kroger that Trudy fell in love with him when he was a detective, but in Mr. Monk and the Class Reunion (2006)(#5.6) Trudy fell in love with him in collage.
In the city of San Francisco, there is no police rank of 'Detective'. The title is 'Inspector'.
Neither Sharona nor Natalie could possibly afford the houses they are shown living in given either woman's meager salary in San Francisco's notoriously high real estate market.
Natalie regularly complains about the salary she makes and is often strapped for cash, however, throughout the series she is seen wearing multiple pairs of Louboutin shoes which would cost at least $550 a pair.
In most law enforcement agencies, Captains and Lieutenants are primarily management jobs. They work behind a desk and rarely are involved in any type of investigations other than in a supervisory capacity. Captain Stottlemeyer and Lt. Disher would not have been at every crime scene conducting investigations as that role is for Detectives/Inspectors.
Despite many people asking or noticing that there is something wrong with Monk with his OCD, neither he, Sharona or Natalie ever try to explain that Monk has a psychological issue which is why he acts so strange even if it leads to misunderstanding while on a case.
The newspaper clippings in Monk's scrapbook (seen throughout the series,) which have headlines about Trudy's murder, are in fact articles describing the state of the economy.
Several times in the series a key location is said to be on Vinton St. There is no Vinton St. in San Francisco. There is a Vinton Ct. but it is a small alley wily two doors with only two addresses.
It is quite obvious to anyone who knows the real San Francisco Bay Area that the series was not filmed there. There are numerous references to extreme temperatures (when the Bay Area is famous for its year-round mild temps) as well as large rolling hills with nothing on them (SF is very densely populated with little left untouched).
Temperature extremes are not uncommon in San Francisco. As Mark Twain famously stated, "The coldest winter I ever spent was summer in San Francisco,"
In the intro, Mr Monk walks out the door, then returns to adjust the position of an umbrella. Mr Monks O.C.D. would not have allowed him to hang it incorrectly in the first place.
Boxes on shelves above couch in Monk's apartment are often placed in different distances from each other. Monk with his urges wouldn't miss it and would arrange it correctly.
Monk drinks bottled water, which isn't as pure as everyone thinks. It has about 200ppm (parts per million) of contaminants (compared to about 400ppm for tap water). Monk of all people would know that.