Factual error: In the flashback where Monk is explaining how the money was stolen, the principal finds the 5 dollar bill he wrote "good luck" on and holds it up for everyone to see. The bill he holds is a 5 dollar bill which was released in 2000, with the enlarged Lincoln. The flashback takes place in 1972.
Factual error: When Monk is talking to Sherry about the painting in the art gallery where the painted woman was going to kill her husband, he says that she has a bruise on her left eye. But the bruise is actually on her right eye. While it is viewable that it is on Monk's left, he would not make that mistake.
Factual error: Since Monk has OCD it would be highly unlikely for him to be on a jury. Plus, Monk works for the police department and since he technically works in the criminal justice system, that would have made him exempt from jury duty.
Factual error: When Natalie hears the jury's muffled screams inside the locked room she uses the fire extinguisher to tear off the door knob. But a locked door without a knob is actually only harder to open, because like that you cannot turn the mechanism even if it was unlocked.