While at the police station waiting to report the UFO sighting, Mr. Monk adjusts the blinds on the door so that they are both on the same level. A few seconds later when the sheriff opens the door to let Dolly out, the right blind is clearly much lower than the left, and both sides are covering the sign on the door. In the next shot, after closing the door, they are once again at the same level, with parts of the signs sticking out below the blinds. Then moments later both blinds are spontaneously lower again, with the bottoms of the signs peaking out from underneath them.
When Natalie calls the Captain from the pay phone, the phone faces away from the street on the building side of the pole. Monk is walking away from her down the same street, with the buildings on his right. When he looks back at Natalie, the buildings are on his left and the pay phone is on the street side of the pole.
At 11 minutes in as Monk is laying down in the bed, the camera is overhead and the box of tissues is on the corner of the bedside table nearest the foot of the bed and next to the phone. When Monk sits up, the box is in the corner nearest the wall and next to the lamp. He gets up, looks out the window, sees the "alien", gets back into bed, lies down, and the box is back at the front of the bedside table as he gets up again - it has returned to the back of the table near the wall.
The actress is clearly breathing while Monk examines the body. You can see her chest rise and fall.
Natalie tells Monk that a firefly is buzzing around them. Fireflies live in wet environments and are rarely found in the western half of North America, and nowhere in California.
When the sheriff is showing Monk the body in the doctor's office, he says it was found in "the foothills about five miles west." But when they're stranded where the body was found, he says, "One of us is going to have go get help. The highway is about fifteen miles that way." He should have just said that someone needs to walk back into town.
Monk says that the packet he finds in the dead woman's boot is a silicone packet, when in fact the packets they put in boots have silica in them. Silicone is rubber, silica is a used as a desiccant.
When Monk is in the sheriff's office, he lowers the window shade on the left to be on the same level as the one on the right. Close observation reveals that the left shade is still about a quarter inch higher than the one on the right. This is very unMonk-like.