Character mistake: At the end, Vala and Mitchell establish a wormhole and let Teal'c and Jackson know. Almost a minute passes before Teal'c and Jackson get back to the gate and Jackson yells "run" because they need to get through the gate right away. Obviously they're detained, but after being let go, Mitchell says they're sending the iris code now. This is something that should have been done sooner, especially after hearing gunfire, so they could be ready to go through when Teal'c and Jackson arrived.
Suggested correction: OR... after hearing the gunfire maybe it was smarter to wait until they verified that it was Teal'c and Jackson who prevailed. Otherwise, they risked leaving the gate open to a hostile force.
Perhaps they waited, but they still would have sent it when they saw them, which the didn't. And they've never waited like that before.
Plot hole: And the end, when Vala and Mitchell activate the Stargate home, SG-1 is delayed in being able to step through because they are detained. However, the whole time they're detained by the gate, there's no radio transmission from SGC. Later we find out they're coming home early, so on SGC's side, they just had an unscheduled off world activation and would know it's from the planet SG-1 is on, and they would radio for an update. None of that was done so the conversation could happen.
Continuity mistake: When SG-1 is tied up, Carter has blood going down her cheek and from her mouth right before being beamed up. In the next shot on board, the blood is gone.
Continuity mistake: The way the C-4 is placed on the blast door changes in various shots.
Continuity mistake: When Hoskin is shot by Carter, the position of his body changes from how we see him to land to the next shot of him when Carter approaches him. At first his arm is extended and his coat lands to cover his gun. In the next shot his ark is by his side and the coat is tucked under but you don't see his gun.
The Warrior - S5-E18
Continuity mistake: When Teal'c and K'tano are fighting and K'tano says "is that the best you can do", you see Teal'c's training staff on the ground and it's already broken, even though that hasn't happened yet. When Teal'c stands up, that's when K'tano breaks his staff.
Other mistake: In a Russian facility in the kitchen no-smoking sign instead of "не курить" reads "не курять", which is gibberish. (00:26:07)
Continuity mistake: When Omoc is approached in the infirmary, he takes off the oxygen mask. But in some shots, the mask is just pulled down and still around his neck.
Touchstone - S2-E14
Revealing mistake: SG1 return and the Touchstone is missing. When you look from the gate the door is open and you can see the statue that holds the Touchstone. When they enter the doors are then opened to reveal the statue.
There But For the Grace of God - S1-E20
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.
Suggested correction: The Goa'uld are well aware of this. All they would need to do is block the event horizon of their Stargate or disconnect the DHD and any incoming wormhole would default to the gate on Earth instead.
Revealing mistake: When the three are seen running to Apophis' ship (after taking out the Jaffas), the branches of the trees are shown to move because of the great speed they ran at. However, none of the leaves on the ground move.
Revealing mistake: You can tell the rocks of the cavern are CGI and they're walking in front of a green screen. For example, when everyone goes back to the cavern, with Nick, in one shot the rocks cover part of Teal'c's head.
Revealing mistake: As Col. Mitchell is chasing the sedan on the motorcycle, he takes a highway exit marked "Ladner/Surrey" which are suburbs of Vancouver, BC. The show is set in Colorado Springs, and confirmed as the episode's location from the police bulletin. (00:29:10)
Continuity mistake: When Col. Mitchell is talking to Col. Carter in the control room, the initial shot shows Carter appearing on a white computer display. The scene then cuts to a close up of the conversation and the display is black. It is also much thinner than the white display. (00:11:45)
Children of the Gods (1) - S1-E1
Plot hole: When Apophis and his Jaffas are leaving SGC with the captive soldiers - there is no way they could have activated the gate without a DHD, but somehow it gets activated, and they escape.
Other mistake: When first discussing the alien ship, the computer screen states "terraforming progress" long before they suspect and later discover the ship to be terraforming the planet. (00:00:04)
Plot hole: The team go through the gate to disable a drone with the intention of being able to close the active Stargate, but once they go through in a submarine, the gate closes behind them, rendering the mission pointless. (00:24:18)
Suggested correction: This entry seems to have been made without watching the episode or you skipped a part. When the 3 enter the Stargate via the submarine, the Gate does NOT close behind them. It stays open, which we not only see but is how they can communicate with O'Neill. Then Dr. Markov says once they bring the drone in (to the submarine), they can shut the drone off and the Gate will close. Which is what they do (off-screen) and when they do, the Gate closes.
Other mistake: Just after the scientists on an alien moon follow The Light into the forest there is a car behind them.
Plot hole: Despite the Russian Government not being aware that the submarine is quarantined in a US port, a Russian Navy Sovremenny-class destroyer is visible in the background. (00:14:29)
Other mistake: When Jonas says he has flashes of what's going to happen (and no-one believes him), Teal'c says they have encountered many strange phenomena but no-one who could see the future. Except Jack and Teal'c had a whole "Groundhog Day" episode where, because they were stuck in a loop, they could see the future. Carter then says it goes against all the laws of physics as we know them, despite knowing time travel and other things that break the laws of known physics exists.