Natalie claims she believes in voodoo after an incident with Mitch. In Mr. Monk and the Wrong Man (2007), after Monk says he can feel the tattooed knife going into his head like voodoo, she says, "There's no such thing."
When the police officer is looking at the news article about the man hit by lightning, the words "VOODOO KILLER" appear above the headline. Yet at the time the article would have been written, the voodoo doll had not yet been found and there would have been no reason for the newspaper to connect the murder to voodoo.
The interior of Reverend Jorgensen's Voodoo Boutique is completely different from the exterior (which was digitally-altered stock footage from Ghostbusters II (1989)).
While visiting Reverend Jorgensen's Voodoo Boutique, Leland Stottlemeyer puts the third voodoo doll on the table. After talking with the store owner, he and Randy turn and leave without the evidence.
During the car chase, the cars pass by the same lighted building several times before ending the chase almost in front of it.
The batting helmet Petey is wearing doesn't have an ear flap. No youth baseball league allows batters to use helmets without ear flaps.
When the Captain orders the entire department to rearrange the desks to Monk's liking, none of the computers or phones are unplugged or plugged back in, even though all the desks are moved around quite a bit. Furthermore, one computer's monitor is on, but the power cords are hanging off the side of the desk.
When Stottlemeyer and Disher first interview Angeline Dilworth, she says she's an ER nurse, but later on it's revealed that she's an EMT.