Mr. Monk vs. the Cobra - S3-E11
Character mistake: Monk says that Croatia is a new country and didn't exist until 1992, but Croatia gained independence in 1991. However, Croatia still existed prior to that, it was just part of the Socialist Federal Republic of Yugoslavia. So things could still be made in Croatia.
Mr. Monk Makes A Friend - S5-E11
Character mistake: At the crime scene, the #8 evidence marker is in the bathroom. When Monk and the Captain are examining the body, a #8 evidence marker is seen on the lamp. They wouldn't use a number more than once at a crime scene.
Mr. Monk and the Election - S3-E15
Character mistake: Captain Stottlemeyer uses gloves to pick up the letter found sticking out of the pipe. He doesn't actually put the glove on, but still uses it to avoid getting any of his prints, skin, etc on the paper. But then he uses his other, non-gloved hand to open up the note and hold it, and Monk also touches the letter. If he cared about not contaminating evidence by using the glove, he wouldn't touch it bare handed and if he didn't care about touching the note bare handed, then he wouldn't have used the gloves.
Character mistake: It seems throughout the whole series at crime scenes Monk, Randy, and Stottlemeyer handle evidence bare handed. Surely, they should be wearing gloves so as not to contaminate the evidence.
Mr. Monk and the Sleeping Suspect - S2-E7
Character mistake: Brian Babbage is such a perfectionist and plans out such an elaborated plan for his crimes that it is very unlikely that he would simply leave the ketchup bottles sticking to the ceiling for the police to be found after he had timed the perfect glue for his plan. Plus, he even had staffers who already knew about the bottles and it would have taken him not more than a single order for the bottles to be removed. (00:23:50)
Mr. Monk Meets His Dad - S5-E9
Character mistake: At some point Monk asks his father what the device in the car is. His dad tells him it's a GPS. It's difficult to believe that our detective doesn't recognize the machine, even if it's probably another model: the whole plot of the episode 2x03, Mr. Monk Goes to the Ballgame, revolves around a tampered-with GPS.
Happy Birthday, Mr. Monk - S8-E9
Character mistake: Given how Monk is it seems unlikely he'd forget about being in a dumpster filled with garbage and be able to enjoy a birthday party, even if it's his own.
Answer: Notice also that in the opening credits scene when he is touching parking meters her also wipes his hand on his clothes each time he does it.