In Mr. Monk Goes to the Asylum (2002) it is stated that Monk is allergic to tomatoes, but here he eats one.
When Natalie takes the pills and the juice, the pills are in her right hand and the juice in her left. Then they switch hands in the next shot, and finally switch back again.
When Monk gets out of the car in front of Dean's house, he stands next to the garden path. In the next shot, he stands on the path, then next to it again.
Monk call his recently-acquired tomato a SQUARE tomato. Actually, it's a CUBE tomato.
What is supposed to a corn seed is shown sprouting. However, the plant that is shown sprouting is a dicot (two leaves when the plant sprouts). Corn, like all forms of grass, is a monocot (one leaf when the plant sprouts).