Plot hole: Near the end, a cop comes to tell Schanke that an explosion has been reported at Nick's place. But neither of the two intruders uses any explosives. One shoots his way in through a door and the other breaks in through a skylight. Neither makes enough noise for the disturbance to be called an explosion. (00:41:15)
Plot hole: When the two henchmen who break into Nick's loft to kill Lisa are captured, the case is closed. But the two thugs were reporting back to a boss who wasn't caught, and who surely would have sent more hitmen after Lisa. So the case shouldn't have been closed.
Plot hole: Nat thinks Nick is becoming more human because he can see himself in the mirror, and he replies, "Only sometimes." This line contradicts series canon, as "Forever Knight" did not adhere to the vampires-don't-appear-in-mirrors cliché. Nick was seen to reflect very nicely, in fact, every time he passed a mirror, and not just "sometimes."
Plot hole: Nick calls Schanke and asks him to take the Polaroids in to a lab for analysis. But Nick seems to have forgotten that he has the photos with him. They're not back at the precinct station for Schanke to take them in. (00:30:25)
Plot hole: The insertion of a musical sequence used to fill extra time in this episode creates a plot problem. It's spliced in between Nick's urgent plea for Nat to stall the autopsy and his rescuing the bound and gagged Rebecca, and unfortunately makes it appear that in that interval, Nick simply went home, played music and sat in his loft window brooding, ignoring the case altogether. (00:40:40)
Plot hole: At the Precinct after the second spa incident, Captain Stonetree refers to "two unexplained reflex murders in one night." But the first victim survived the attack - so there was only one murder, not two. A little worse than a simple character mistake, since he's the police captain and knows the case. Schanke gets it right later, when he says, "One murder and one attempted murder." (00:14:20)
Plot hole: In the morgue, Nick tells Nat that vampires disappear when they die. Not so in this series. "Forever Knight's" vampires, defying old movie clichés, remained stubbornly intact when staked, making Nick's statement here a glaring contradiction of canon. (00:16:05)
Can't Run, Can't Hide - S2-E10
Plot hole: In the underground bunker, Nick demands to know why the vampires in Vietnam are feeding on the children "when there are so many dead up there". Yet later in this same episode (as well as at other times in the series), it's stated that "Forever Knight's" vampires can't drink from the dead. (00:20:35 - 00:27:40)
Plot hole: At the end, Nick and Schanke discuss the bruise Nick's blow supposedly left on Damir's jaw. But Nick didn't hit Damir. He grabbed and tossed him bodily into a trash heap in the alley - without ever once touching his jaw. (00:41:50)
Near Death - S2-E23
Plot hole: Dr. Linsman puts a heart monitor on Nick for the experiment, but for some bizarre reason, never questions why her "patient" has a resting heart rate of only one beat every ten minutes.
Blind Faith - S3-E5
Plot hole: In a major violation of series canon, this episode ends with the vampire doggie (a silly enough premise to begin with) bringing its owner across, a process previously established as complex enough to be far beyond even the smartest canine's capabilities. (00:40:00)
Plot hole: Bullets, which have been passing harmlessly through Nick for two whole seasons, suddenly do him great injury here. And though he's taken to surgery, the bullet lodged in his head is never removed. It's still there on the latest x-ray when LaCroix arrives to "consult" with the doctor. (00:00:05)
Plot hole: Because he has no discernible vital signs, the wounded Nick is declared dead in the hospital. When he revives, he's rushed into surgery, where he'd surely have been reattached to a monitor. Somehow, though, no one on the medical staff notices that their patient still has no normal pulse or heartbeat. (00:05:05)
Plot hole: When LaCroix arrives at the amnesiac Nick's loft, Nick recognizes him as "the doctor from the hospital." But Nick was still comatose when LaCroix posed as a doctor and came to his room, so he shouldn't remember that particular "doctor." (00:19:45)
Plot hole: Nick has spent two seasons with the supernatural ability to see perfectly well in the dark. But here, exploring the haunted house alone, he suddenly needs a big neon-blue-beamed flashlight to see where he's going. (00:31:30)
Plot hole: Nick mysteriously forgets that he can fly in this episode. With the ghosts of his past victims in hot pursuit, he trips and tumbles all the way down a full flight of stairs. Any other time, he'd simply have flown away. (00:38:10)
Plot hole: The handyman tells the police that he has turned on the power to restore lights in the house. Why, then, is everyone still crawling through the place with flashlights?
Plot hole: Throughout the first two seasons, Nick was always able to sense other vampires and to instantly differentiate between vampires and humans. Here, he inexplicably fails to detect that the returned Janette is now mortal. She has to tell him. (00:27:10)
Answer: Nick was sick and tired of being an immortal bloodsucker. He wanted to be human, fall in love, get married, have children, grow old and die. As for Janette, according to her, she fell in love and the passion she felt "cured" her of her blood lust.