On a mission to retrieve a crashed UAV probe, SG-1 encounters a race of simple, friendly aliens who appear to be less evolved than humans. However, the aliens begin to fall ill shortly after their arrival, causing the team to suspect that they may be somehow responsible.
"One False Step" provides examples of the following tropes:
- Answer Cut: When Daniel is attempting to communicate with the aliens.O'Neill: You gotta wonder what they're talking about in there.[cut to inside the cave, where Daniel is doing his best impression of the UAV while the aliens look on in bewilderment.]
- Barbie Doll Anatomy: The nearly naked aliens appear to lack both nipples and genitalia.
- Bizarre Alien Biology: The aliens look more-or-less human on the outside, but they have a heart-like organ in their abdomens which is sensitive to various sound frequencies. They also have a symbiotic relationship with a native plant due to the frequency it gives off.
- Blunt Metaphors Trauma:Daniel: Teal'c, could you do me a favor? Keep an eye on this plant thing for me.Teal'c: I will keep both of my eyes on it, Daniel Jackson.
- Brown Note: When the UAV crashes into one of the alien plants it causes a change in the subsonic frequency given off by the plant. The resulting sound causes several of the aliens to fall critically ill in addition to causing headaches and irritability in O'Neill and Daniel.
- The Cassandra: O'Neill is pretty dismissive of Daniel's claims that he witnessed one of the plants grow and shrink again, though it's implied that this is at least partly due to the effects of the sound frequency.
- Emotionally Tongue-Tied: O'Neill and Daniel make an exceedingly awkward attempt to apologize for sniping at one another while affected by the plant's frequencies:O'Neill: Listen, I um...Daniel: No, no... Sorry, you were...gonna say.O'Neill: It's just that, uh... well. You know.Daniel: I know, I know. I know. You know that I...?O'Neill: I know. There must be something...Daniel: Something wrong with us.O'Neill & Daniel: (simultaneously) Physically.
- "Eureka!" Moment: When Daniel realizes he got a headache watching the recorded footage of the aliens' plants.
- Exposed Extraterrestrials: Subverted. The aliens initially appear to be naked, but it's later determined that they're covered in some kind of body paint that hardens over the skin.
- Hate Plague: A mild version where prolonged exposure to the plant's frequencies makes Jack and Daniel extremely irritable and kind of mean to each other, but not violent or dangerous.
- Humanoid Aliens: The aliens mostly resemble shorter-than-average humans, but their actual biology is very alien.Fraiser: They may look... similar to us, but they're definitely very different.
- Innocent Aliens: The aliens are described as being "not quite as evolved" as earth humans and are largely portrayed as being "simple" and childlike.
- Nice Job Breaking It, Hero: When the aliens begin falling ill, the team assume that they must have introduced some kind of pathogen that they have no resistance to. Then it turns out that the real cause is the UAV crashing into one of the plants that the aliens have a symbiotic relationship with and damaging it... So it's still the heroes' fault, just not in the same way that they thought it was.
- No Biochemical Barriers: The team initially suspect they must have passed some kind of disease to the alien population, and Fraiser lampshades this trope by pointing out that it's a miracle it hasn't happened before. Ultimately subverted in this instance, however, as it turns out the alien illness has a different cause.
- Shown Their Work: While the effect isn't quite as dramatic in real life as it is in this episode, infrasound (sound waves at a lower frequency than 20Hz, the lower limit of human hearing), can cause odd unexplained feelings in humans, usually fear, anxiety, and irritability. There are also more subtle feelings caused by these frequencies...usually the feeling you're being watched or something is in the room with you. Since natural disasters like earthquakes and volcanoes, and large predators produce infrasound, it's been proposed that these subconscious reactions to it evolved for survival reasons (getting away from the sound would get you away from the disaster/predator). Jack and Daniel getting headaches and irritability while exposed to the infrasound is actually quite realistic.
- Suddenly Shouting: Daniel does this when it looks like there's no hope left for the afflited aliens.
- The Speechless: The aliens have no formal speech or language, though they are capable of making other vocal sounds such as singing and screaming.
- Talking to Plants: Carter provides The Stinger when she reveals how she realized that the aliens have a symbiotic relationship with the plants.Daniel: Wait a minute, how did you realize?[Beat]O'Neill: Captain?Carter: ...I-I talk to my plants, okay?
- Tantrum Throwing: Daniel smashes up his lab after watching footage from the planet containing the plant frequencies.
- Title Drop:Daniel: "One wrong move, one false step, and a whole fragile world gets wiped out? WE ARE KILLING A WHOLE RACE OF PEOPLE HERE!"
- Volleying Insults: Jack and Daniel descend into this while they're being affected by the plants.O'Neill: It means that on a good day, you can be a little... flaky.Daniel: And on a good day you can be a little ignorant and condescending!
