|Out of universe information|
P3X-500 was a desert planet, the closest one in the Stargate network to P3W-451. SG-1, shortly after rescuing SG-10 from the black hole which was engulfing P3W-451, crash-landed a Tel'tak on the planet after Dr. Daniel Jackson observed that it most probably once housed a Celtic civilization. From there, they were able to return to Earth through the Stargate where they faced their punishment for stealing Kinahhi Anti-gravity shield.
After Colonel Jack O'Neill and Major Samantha Carter were transferred to Kinahhi to face their sentence, Dr. Daniel Jackson and Teal'c came back to the planet in order to use the damage Tel'tak to rescue them. Though SG-2 came through the gate in a half-hearted attempt to stop them, purposefully missing hitting their target, they managed to escape into hyperspace and made their way to Kinahhi. (SG1: "The Cost of Honor")