P3X-595 was one of the first planets visited by SG-1 soon after the formation of Stargate Command.
What happened on SG-1's mission to P3X-595 has never been fully explained, nor whether or not they met an intelligent species. The only time the mission was referenced was after SG-1 rescued Capt. Carter from Turghan (1.04 "Emancipation").
Below is the exchange:
What a relief. I have never been so happy to see you guys.
Oh, sure you have! Remember that time on P3X-595?
You drank that stuff that made you take off…
Ahem. We won't get into that now.
--Aurora 14:25, 27 April 2006 (PDT)