In the Stargate control room, a female USAF Tech Sergeant hands a phone to Hammond; she is wearing a pale blue long sleeve blouse and a dark blue sleeveless dress. That outfit is the USAF semi-formal maternity uniform designed specifically for pregnant personnel.
The shot of Amanda Tapping (Carter), in the opening credits, starting with 'The Enemy Within', running into the gate room, looking at the gate then away and up comes from this episode. This may seem odd until you realize that Showtime, the original network for the show, ordered the first two seasons up front and, likely, most of those episodes were produced before the show starting airing.
When Col. O'Neill says, "Stand down, campers, we're on hold." this is the first of many times he will call people, "campers."
Katie Stuart (Cassandra) also played Phoebe in The Outer Limits (1995) Lithia (1998), which also aired on Showtime on July 3, 1998.