Plot hole: The murderer mails a garage door opener with the button taped down to his victim and kills her by remote. But A) With the switch continuously in the "on" position, the battery would die long before the package arrived, and B) Door openers use special frequency tones that are set much like a safe combination. The likelihood of one control opening 3 different doors in the same area, as it does here, is virtually nil. (00:33:30)
Plot hole: The whole plot hinges on Steve Wagner knocking the victim out for 2 days, remotely hanging her while he's in space, then removing the hanging machine when he lands. But keeping someone unconscious chemically for 2 DAYS is a hell of a feat. And unpleasant though it is, she'd be voiding her bowels over those 2 days, leaving a serious mess, plus all the chemicals necessary to keep her unconscious would be found in an autopsy.
Plot hole: When Stottlemeyer and the other cops arrive at the recycling center, the patrol car's siren turns on and off. The killer had said to Monk that if he called the cops, he'd kill Natalie. Coming to a hostage situation with the siren going would be a really bad idea. (00:37:45)