Mr. Monk and Little Monk - S4-E8
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.
Mr. Monk and Little Monk - S4-E8
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.
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.