Monk says that Captain Stottlemeyer's mother died 37 years earlier. However, in Mr. Monk and the Captain's Wife (2004), she was mentioned as still being alive.
When Monk steps in the dog poop he goes down screaming. When Natalie gets there to help you can see the bottom of his right shoe and it's clean. Natalie then looks at the bottom of his shoe and the heel is covered with the dog poop.
After Monk meets with the editor (rejecting his book) he walks to a window and opens the latch, contemplating suicide.
Windows in high-rise buildings, such as this, can't be opened as a way to prevent suicides.
When Monk and Natalie visit the animal shelter, there are no dogs barking at any time during their visit.
The murder weapon is roulette. If you measure with a tape measure that has been modified, as in the movie, an inch is larger on the roulette, then the length of the rope becomes smaller.
In the flashback of Truesmith drowning in Barbados, you can see the pool wall, and the line on it, in the background.
The delivery boy tells Monk that it's the last refill, yet when Monk puts the bottle in the medicine cabinet, the bottle clearly says 3 refills.
No explanation is provided on how Lucas put the trophies back on the windowsill while leaving the garage through the window that opens inwards. In fact, it would be impossible.
When Monk, Natalie and Randy first arrive at the estate, and are surprised by the appearance of Stotlemeyer, they walk away from the car leaving it behind and blocking the drive away.
When Rick Eden is introduced, his video has him telling us that he was an RAF pilot while footage is shown of a pilot taking off ... from an aircraft carrier. The RAF generally leaves carrier-based operations to the Fleet Air Arm.