"Don't tell me you haven't noticed how strangely people have been acting around here."
— Jonas Quinn
Carter, Teal'c and Jonas head to the small coastal town of Steveston, Oregon, to investigate the suspicious disappearance of Dr. Richard Flemming, who has ties to the same corporation as Adrian Conrad. It soon becomes apparent that Flemming was murdered, and the team suspect that there must be something sinister going on to explain the strange behavior of the townspeople.
"Nightwalkers" provides examples of the following tropes:
- Badass Longcoat: Carter, Teal'c and Jonas all wear black leather trench coats for the duration of their investigation. Also Conspicuous Trenchcoat given how badly it makes them stand out.
- Chekhov's Gun: The mysterious syringe that Carter signs for at Flemming's house turns out to be filled with a chemical that kills the cloned symbiotes, allowing Carter to inject herself with it before she can be implanted.
- Chekhov's Gunman: Sheriff Knox's deputy and the barkeep turn out to be NID Agents Cross and Singer, respectively, and reveal that they have been monitoring the situation in the town for the last several months.
- Continuity Nod:
- Several mentions are made of the research conducted by Adrian Conrad's team in "Desperate Measures".
- Carter states that O'Neill is still with the Tok'ra as they attempt to find a replacement host for the symbiote he was implanted with.
- Disconnected by Death: The phone call that Flemming makes to Carter in The Teaser gets cut off as his car is run off the road.
- Donut Mess with a Cop: The first thing that Sheriff Knox does when Carter pays him a visit is ask his deputy to bring in the donuts.
- Fish out of Water: Jonas comments on this when he and Teal'c are met with suspicion by the bar patrons, pointing out that no matter how much time they spend on Earth, they'll never truly fit in.
- Hyper-Awareness: Jonas demonstrates this thanks to his eidetic memory, catching onto the fact that there's something not quite right about the townspeople long before the other two.Jonas: Don't tell me you haven't noticed how strangely people have been acting around here.Carter: What are you talking about?Jonas: Well, for instance: that man there, right behind Teal'c — he doesn't realize it, but he's just put eight cubes of sugar into his coffee. And that lady over at the counter, she's been reading the same article for over half an hour. Since we sat down, that waitress has dropped her tray twice, the cook has gotten three orders wrong — including my hamburger, which I ordered medium-rare but is in fact well done. I've been noticing similar behavior all morning. It's like the entire town's half-asleep.
- Jurisdiction Friction: Downplayed; Sheriff Knox points out that the Air Force doesn't have any real jurisdiction in investigating Flemming's disappearance, but mostly cooperates when Carter tells him that it could be a matter of national security.
- The Mole: It turns out that Agent Singer had already been implanted with a symbiote, so the Goa'uld had been aware of the NID monitoring them for quite some time.
- Note to Self: Carter theorizes that Flemming sent the anti-Goa'uld "vaccine" to himself in order to keep it hidden while his house was searched.
- Oh, Crap!: When Carter decodes one of the discs that the team find at the shipyard to reveal pages and pages of Goa'uld writing, causing her to realize that all of the townspeople are hosts.
- Properly Paranoid: Carter suggests at one point that Flemming may have been simply suffering from drug-induced paranoia, to which Teal'c replies that paranoia was clearly well-founded, given that he's since disappeared and his lab his been burned to the ground.
- The Stakeout: Teal'c and Jonas stake out the shipyard after the team find a half-built alien ship there.
- The Teetotaler: Teal'c orders a ginger ale at the bar.
- Town with a Dark Secret: It's revealed that all of the townspeople are hosts to Goa'uld symbiotes that were cloned from the one Adrian Conrad was implanted with by Flemming and his fellow scientists; but since the symbiotes are still immature, they can only take control at night when the hosts are asleep.
- A Weighty Aesop: After Jonas orders a particularly unhealthy meal at the diner and comments that he's really enjoying the "traditional all-American food", Carter tells him that America has another tradition of hardened arteries.
- You Can't Go Home Again: Jonas states that this is the main difference between himself and Teal'c, as he doubts that he will ever be able to return to his home planet.
