While investigating an energy signature on an inhospitable planet, the team discovers what they assume to be an alien time capsule and take it back to earth for study. Things go badly wrong when the device unleashes a defense mechanism that critically injures O'Neill and results in a sentient, bacteria-like organism spreading throughout the base.
"Message In A Bottle" provides examples of the following tropes:
- Bottle Episode: Fittingly enough, considering the episode's title; with the exception of the cold open, the action takes place entirely on base.
- Bloodless Carnage: When the device first nails O'Neill to the wall, Fraiser marvels at the fact that there is virtually no trauma at the site of the injury. It's later revealed that this was deliberate, as the alien organism needs to keep O'Neill alive in order to communicate through him.
- Blue-and-Orange Morality: The organism is not malevolent per se, but it has no qualms about consuming everything on earth to for its new colony if no other alternatives are offered.
- Blunt Metaphors Trauma: Teal'c again, though he claims to have been joking this time."Undomesticated equines could not remove me."
- Chekhov's Gun: Early in the episode, Daniel complains about the team's upcoming mission to a primordial world with no signs of civilization. He later realizes that this would be the perfect environment to send the organism to where it could live in peace without disturbing any other lifeforms.
- Elevator Failure: Carter briefly gets trapped in one of the elevators as the base systems begin to fail. Conveniently, Daniel happened to be passing and was able to break her out with a fire axe.
- Energy Absorption: Attempting to shoot the device with a staff weapon merely provides the organism with more energy, allowing it to spread further.
- "Eureka!" Moment: Daniel realizing that the organism is sentient and trying to communicate with them through the base computers.
- Friendship Moment: Between O'Neill and Teal'c.O'Neill: You're a good man, my friend.Teal'c: As are you... my friend.
- Going to Give It More Energy: Upon realizing that they're dealing with a sentient lifeform, Carter and Daniel have Teal'c deliberately shoot the device with his staff in order to allow the organism to grow to such an extent that it's able to communicate through O'Neill.
- Impaled with Extreme Prejudice: In response to the team trying to throw it back through the stargate, the device ejects several harpoon-like spikes, one of which pierces straight through O'Neill's shoulder and into the concrete wall.
- Oh, Crap!: Hammond's reaction when Carter points out that if the self-destruct goes off, it could provide the organism with enough energy to spread over the entire planet.
- Also a minor one when Daniel is teasing Sam about a possible crush one of the techs has on her, only for said tech to loudly tell them he's recording everything happening in the room.
- Ragnarök Proofing: The device is over 100 thousand years old and still giving off an energy signature when the team finds it, having survived the annihilation of its entire planet.
- Self-Destruct Mechanism: The self-destruct starts counting down after Hammond orders the base sealed off. Carter points out that not only will this fail to destroy the organism, it will actually provide it with all the energy it needs, but by that time they are unable to override the commands.
- Shout-Out: The plot features multiple references to The Andromeda Strain, including Hammond initiating a "Wildfire" protocol to seal the SGC off, as well as the organism being capable of converting multiple forms of matter and energy for its own use, necessitating a last-minute cancelling of the base self-destruct to keep it from multiplying out of control.
- Starfish Aliens: Fraiser describes the alien organism as being "mobile like bacteria but small like a virus"; it acts in a similar way to necrotizing fasciitis but attacks living and non-living materials indiscriminately; it's able to absorb energy and use it to grow exponentially, and it's sentient.
- With Due Respect: Carter spends most of the episode arguing with Hammond about the best way to deal with the situation. Fraiser also gets into a brief argument with him when he refuses to breach containment to allow much-needed antibiotics onto the base.
