Plot hole: Huge plot error: Apophis and Clorell (Skara) should not have survived the explosion in Season 2, Episode 1 (when they attack Earth with two ships). In "Family" they explain that Apophis and Clorell survived by escaping through the stargate aboard Clorell's ship moments after Daniel Jackson did the same. However, when Daniel Jackson escapes through it, Apophis and Clorell are not even on the right ship, and there is 1 second left on the C4 timer when Daniel escapes. They actually show Daniel Jackson escape, and then cut to Apophis and Clorell still aboard their ship. So apparently, Apophis was able to "ring" from his ship over to Clorell's ship, make it to the stargate room, dial an address, and escape through the stargate all within literally 1 second. Is this guy related to The Flash?
Other mistake: When the hallucinated Jonas is leading Dr. Kieran upstairs, a red light can be seen glowing on his hip where his Beretta is holstered. It looks as if Corin Nemec is carrying an Intar (a training weapon with a glowing red crystal in the grip) prop instead of a normal pistol. Can't be due to a hallucination - Dr. Kieran couldn't hallucinate a Goa'uld training weapon he'd never seen.
Plot hole: When the team manage to create the cavern with the buried stargate they send Teal'c through to drill his way out, but wouldn't it be safer (and significantly faster) to fire a missile or two through and blast their way out? They have no idea how deep the stargate is buried, or under what type of rock, so sending Teal'c with only four hours of air seems suicidal. (00:35:00)
Factual error: The star collapsing into a black hole suddenly seems to increase its gravitational pull on the planet that SG-10 is on. When an object collapses to a Singularity, the pull it exerts on an object does not suddenly change because the mass, and therefore the strength of its gravity, has not changed.
Continuity mistake: When the Goa'uld attack the alternate Earth they dial in so no-one can escape. However in future episodes the Russian Stargate program said that as long as a DHD was hooked up to their gate it would have priority. When the invasion happened they had a gate on the ship hooked to a DHD.
Factual error: At the end of the episode General O'Neill is introduced to Joe's wife. He is introduced as General O'Neill, but his insignia on his dress blue uniform is a Colonel - an eagle, not a General's star.
Stupidity: Some ancient advanced civilization took to the task of building this amazing net of stargates that enables instantaneous traveling over hundreds of light years or more, but any stargate can be disabled by anybody just by covering it with dirt or rocks. Apparently if the stargate is buried then it becomes inactive. See Season 1 EP.1.