Continuity mistake: When Carter gets stuck in the elevator, she's on level 22. Every time the level changed, you can hear a beeping noise and there's no noise after we see 22. But from outside, the doors say 28. It wasn't a cut away shot either.
Continuity mistake: When the sarcophagus explodes, the blast door they escape through has no card reader. Once they stand up it's there. (00:37:55)
Continuity mistake: During the surgery, when they attempt to remove the Goa'uld, they start a timer. The timer starts at 00:00:00, then it blacks out (obviously, you don't want to be bored by major neck-surgery), and then the timer is at 01:19:49. However, seconds later (after Carter and Daniel's conversation), look at the timer in the background, it reads 00:23:46. (00:32:35 - 00:33:10)
Continuity mistake: In a scene where Sergeant Walter Harriman tells General Hammond that SG-1 is ok, but Dr. Friesen is dead, Sergeant Walter Harriman is wearing the uniform of Major Davis (you can see "Norman Davis" written on left side of his chest). [His name was originally Norman Davis. At one point, Hammond refers to him as "Airman". This was misinterpreted as him being called "Harriman." Then, in the episode 2010, O'Neill calls him Walter. Thus, his name changed from Norman Davis to Walter Harriman. Still a mistake, but that's why.] (00:30:15)
Children of the Gods (1) - S1-E1
Continuity mistake: Kawalsky's rank changes. At the beginning of the episode, he wears the rank insignia of a Captain. However, when his is in dress blues for mission briefing he has on Major insignia. Then in the meeting after the Abydos, he's back to wearing Captain bars.
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.
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.
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.
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)
Touchstone - S2-E14
Continuity mistake: The Stargate on the Weather Controlled Planet has the Earth symbol (Similar to Å) on it, while it should be exclusive to Earth. (00:02:18)
Children of the Gods (1) - S1-E1
Continuity mistake: As the female soldier approaches the gate when its first activated, an alien device is thrown through. You can see in the shot that the device will land much further away from her foot than what is shown when the shot changes. (00:02:25)