While exploring an alien Stargate complex on P3R233, a world that appears to have been destroyed by the Goa'uld, Daniel Jackson discovers a slab that, when activated, turns into a shimmering mirror. He touches the mirror and gets a mild jolt but thinks nothing of it until he returns through the Stargate. Then, he finds himself in an alternate reality, a place that looks like Earth but where nothing is quite as it was.

The most distressing difference is that this world is under attack by the Goa'ulds, who have wiped out half-a-billion people and are about to capture the Stargate Command. O'Neill faces-off against Teal'c, who in this reality is still loyal to the Goa'uld, and Daniel tries to escape through the Stargate with information that may save his world from the fate of this alternate reality. Part One of Three.

original airdate--February 20,1998           Planet visited:

music--"Stargate SG-1" theme song by Joel Goldsmith

Goofs--When attempting to dial out about 26 minutes into episode, the Earth gate point of origin symbol locks (indicating that all the symbols are finished encoding). But then "chevron 2 encoded" is announced.

Trivia--When Senator Kinsey asks Colonel O'Neill if he's ever seen a Goa'uld starship, he responds that he has. Immediately following his remark, there's a scene of a ship landing on top of a pyramid. This is footage lifted directly from Stargate.

• In a season 1 episode Daniel makes a sarcastic remark that they will be able to upload a computer virus into a Goa'uld mothership to stop an invasion. This is an obvious reference to the film Independence Day which was directed by Roland Emmerich, who also directed the original Stargate film.