Deliberate mistake: When Sharona spots Disher's personal ad in the newspaper, there is a shot of it. She then reads the description of him from the ad, which matches what's on the screen, however, the second part she reads, "Seeks petite blond with no-nonsense attitude, kids ok" is not in the ad shown. (00:22:20)
Continuity mistake: Stottlemeyer says "does that make any sense to you?" as Monk is straightening the pots on the mantelpiece - all the lid handles are horizontal. The camera cuts away for a second, cuts back, and the lid on the far right has suddenly rotated 90°, whereupon Monk straightens it to be horizontal like the others.