The Douglas McLean Memorial Observatory on planet P3X 987 is named after the series art director, Doug McLean.
The breed of dog given to Cassandra is a Shiba Inu, a Japanese dog not common in the United States at the time of production.
Teal'c refers to Nirrti as "he", but in later episodes, the Goa'uld Nirrti is a female portrayed by Jacqueline Samuda. As Goa'uld are parasitic creatures that take hosts, it is likely Nirrti had a male host at one time.
The DVD episode order differs somewhat from the broadcast order. This was the 14th episode broadcast, but is Episode 15 from Volume 4 of the Season 1 box set.