Revealing mistake: When Carter is looking up Hathor on the Internet, the address bar says that the web page is on the C drive of the computer rather than a web URL.
Children of the Gods (1) - S1-E1
Factual error: The escort for Colonel O'Neill is wearing both Major and Staff Sergeant rank insignia. Probably what the writers thought was a "Sergeant Major", which does not exist in the Air Force. Major is a commissioned officer, sergeants are non-commissioned officers.
Factual error: When O'Neill throws the knife at the system lord at the end, the knife is spinning in the wrong direction.
Children of the Gods (2) - S1-E2
Revealing mistake: When Daniel, Jack, and Sam first meet the robed Jaffa in the woods, you can see the camera light in Daniel's glasses.
Revealing mistake: A couple of seconds before the beginning of the opening titles you can see that the eyelids of one of the dead Limvris are moving.
Continuity mistake: In Season 8 - Threads, when Sam is talking to Jack in his backyard (barbecue scene), the back door behind her opens and closes between shots.
Unnatural Selection (2) - S6-E12
Other mistake: When Thor reveals to SG-1 that the Replicators have reversed the time dilation device, he says time is moving at a factor of "10 squared" (100 times faster than real time). Carter says that in the hour that passed, 4 days have passed for the Replicators (which is correct), but then says depending on when they did it, hundreds of years could have passed. But that's not possible since that means years in real time would have passed. But the Asgard didn't set this trap years ago, just recently.
Birthright - S7-E10
Other mistake: One of the female Jaffa has a bare midriff showing, but there is no pouch for the symbiote.
Character mistake: Sometimes in the show, when a Goa'uld or Tok'ra is speaking (as opposed to the host speaking), they will say "my symbiote", such as when facing danger or illness: "my symbiote will protect me" or "my symbiote will heal me." However the Goa'uld and Tok'ra are the symbiote and they should be referring to themselves protecting or healing the host's body.
There But For the Grace of God - S1-E20
Continuity mistake: When Daniel returns to the SGU in the alternate reality and Cathrine shows him the map of where the Goa'uld attacks on Earth are, we can see that there are no attacks in the north of Europe, but when we see a closeup Oslo, Stockholm and Helsinki have suddenly been added. (00:14:10)
Factual error: Before SG-1 switched to P90 PDW's, they carried MP5 submachine guns. They were often shown with a full magazine taped upside down to the one in the weapon, so that to reload, all they have to do is remove the magazine, turn it over and insert the full one. Team members were also shown doing just that in several fight scenes. Problem is, real special ops troops are specifically taught in training never to do this. It's far too easy to damage the lips on the spare magazine, rendering it useless. There are clips that will hold magazines upright side by side, but its easy to see on screen they weren't using them.
Singularity - S1-E15
Plot hole: After Cassandra has her first "heart attack" you see her in her room. Why isn't there one of those heartbeat monitors in her room?
The Devil You Know (2) - S3-E13
Continuity mistake: When Jack passes out in the pit, he has dirt all over his face before he passes out and no dirt at all in the next shot. (00:24:15)
Continuity mistake: When they are about to blow up the ancient device at the ruins, Col. O'Neill sticks a wad of C4 to the wall in the corner, when the shot changes, the explosives have moved approximately 6 inches to the left.
Touchstone - S2-E14
Plot hole: When half of SG-1 return to Medrona to detonate a charge aimed at the gate, why didn't they just go to another planet? As when they went to Medrona, there was a blizzard going on and they also had the natives saying they will arrest them as they still hadn't returned the Touchstone. Could have just saved themeselves some hassle.
Children of the Gods (2) - S1-E2
Revealing mistake: When Apophis' queen goes back into the female Jaffa, it is obvious that the film footage was just played in reverse.
Continuity mistake: In the scene where SG-1 tries to get their note through the gate, watch Daniel. The camera cuts to him just before Jack slides down the zip line, and you can see small dots on Daniel's face - presumably the marks left when shot by the security system. However, Daniel has been taking cover since the alarms sounded and only gets hit when he tries to get to the gate after Jack is brought down. The next time Daniel appears on camera, his face is clear again and stays that way till the point in the scene where he, too, is killed by the security system.
Audio problem: Near the very end, when SG-1 have been captured, Daniel says "it's a good day to die", but the subtitles say that O'Neill says the line.
Factual error: Earth's Stargate is dialed up more then once in series 1. Mostly in the first episodes, the passive gate is also shown with a rotating dialer ring when being called. This is not correct. The called gate only illuminates the chevrons. (This is classed as a 'factual' mistake within the show, not a 'continuity' error, and the option to change type has been removed.)
Touchstone - S2-E14
Plot hole: The NID guys escape because Jack can't kill them. He fires his MP-5 around them to try to make them stop. Is there a reason he didn't bring a Zat gun along? The whole point of this mission was to stop the NID rogue agents without killing them and to capture them if possible. The Zat gun seems tailor-made for a mission like this.
Chosen answer: It's never actually mentioned on the show, though in the 'Continuum' universe, she says she's been with Ba'al for 50 years.
MoonFaery ★