Dark Knight: The Second Chapter (2) - S1-E3
Continuity mistake: The blood stains on Nick's white turtleneck are lighter, then darker, then lighter again, and migrate to different positions, both during his fight with LaCroix in the abattoir, and throughout the hospital scenes afterward. (00:10:15 - 00:19:30)
Continuity mistake: While he's in the confessional, Schanke's raincoat collar is turned up. When he rushes out to confront Nick, it's folded neatly down again. (00:37:40)
Continuity mistake: Schanke calls Nick to tell him they've found Mrs. Hedges' body, and says, "They cut her throat, man." We even see a brief shot of the bloodied corpse. But later in the morgue, Nick says, "She was asphyxiated, right?" and Nat agrees. The corpse on the autopsy table now appears to have an intact throat. So, which way did Mrs. Hedges die? (00:22:15 - 00:38:10)
Continuity mistake: When Nick breaks into the old Chinese herbalist's warehouse, he twists and breaks a doorknob lock. But when he walks through to the inside, there's a latch-and-bar array instead of a knob. It's a completely different door.
Continuity mistake: Elizabeth the leper is wearing a dirty gray dress under her black cloak - until Nick makes her a vampire, when suddenly there's a beautiful, spotlessly clean white gown under her cloak. (00:09:30 - 00:26:30)
Continuity mistake: Nick's beard is fully grown in the beginning of this episode, but it changes, disappearing entirely more than once and then reappearing in various stages of growth, even in sequences supposedly occurring on the same night.
Spin Doctor - S1-E15
Continuity mistake: Nick takes to the air wearing a blue windbreaker, but lands wearing a long black duster coat. (00:14:05)
Continuity mistake: Nick gets a phone call telling him another murder victim has been found and that she's been dead for at least a week. In the very next scene, Schanke says that the victim "disappeared after a date last night." (00:27:00)
Continuity mistake: The tow truck and the red van it's towing change positions at the alley's entrance between shots. (00:01:00 - 00:23:35)
Continuity mistake: The wooden plank with which Alexandra impales Nick completely changes angles (from flat side tilted left to flat side tilted right) between the time it strikes him and the time he pulls it out. It also appears to "grow" an inch or so wider than it was before. (00:39:00 - 00:40:25)
Father's Day - S2-E7
Continuity mistake: The godfather's thugs storm Nick's loft and riddle him with bullets. We actually see the bullets coming out of his back, leaving holes in the back of the vest he wears. But when the "vamped out" Nick turns around to face the camera, there are no bullet holes in the front of his vest. (00:23:20)
Father's Day - S2-E7
Continuity mistake: During his fight with Constantine's henchmen, the bullet holes in the back of Nick's vest disappear and reappear several times between shots. (00:23:30)
Continuity mistake: It's 9:10 a.m. outside the police precinct station, and after a 4-minute interview scene with no time lapses, it's 2:55 p.m. inside. (00:21:50 - 00:25:10)
Continuity mistake: Although they never reverse their direction, when Nick and Schanke are walking down the Toronto city street, they pass the same bright yellow discount store sign twice.
Continuity mistake: In the flashback to 1228, Nick's just-awakened sister Fleur has her hair down over her ears, and is wearing a white night dress that covers her to the neck. Cut to a close-up and her hair is pulled back to reveal pierced earrings (unlikely in 1228, and did she sleep with them on?), and she's suddenly in a bare-shouldered gown instead of her night dress. (00:08:35)
Blood Money - S2-E17
Continuity mistake: When Nick and Schanke begin interrogating Sean, the tape recorder on the desk isn't running. It's going a few shots later, though, even though no one's touched it to turn it on. (00:30:30)
Blood Money - S2-E17
Continuity mistake: When Sean sneaks back into the night club owner's office, we can see as he enters that there is no one in the left-hand side of the room. Yet, as Sean sits down at the desk, Walken somehow emerges from the left corner, which we have just seen was empty a moment before. (00:39:15)
Partners of the Month - S2-E18
Continuity mistake: Schanke's mother-in-law had previously been established as dead, yet Schanke's talking to her on the phone in this episode. (00:16:25)
Partners of the Month - S2-E18
Continuity mistake: While he's talking to Janette at the Raven, the level of fluid in Schanke's cocktail changes all by itself from several inches down to nearly full again, even though he's been sipping at it throughout their conversation. (00:34:55)
Continuity mistake: Nick and Schanke are interrogating a murder suspect and disagreeing about whether or not she did the deed. They leave the interview room together, and Nick's hair completely changes styles as he walks out of the room. On the inside of the door, it's combed down over his forehead and rather "fluffy." The minute he exits on the other side of the door, it's brushed back and slicked down. (00:25:55)
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.