Plot hole: Anytime an SG member starts acting weird or something happens that is "impossible", SGC personnel always act skeptical about it. Considering what they have seen in the course of the show, "that's impossible" should have long ago fallen out of their vocabulary. And while I realize that Sam and Daniel are scientists, they have seen enough examples of incredibly advanced technology that they should be far more open-minded when looking for explanations.
Continuity mistake: When Samantha Carter is locked in the storage room on deck 7 and she uses the plasma cutter to make a hole in the door, there is a fingerprint on her visor which appears/disappears between shots. (00:25:30)
Revealing mistake: When Jack and Teal'c are first shown in the fighter when it first enters space, if you pay attention to the stars in the background, they tend to move in a rather jerking fashion.
Continuity mistake: When the Jacks are talking to each other right at the end, the camera goes back and forth from looking over each of their shoulders at the other one. If you look closely, the false Jack's earlobe structure changes when we see him from behind.
Stronghold - S9-E14
Continuity mistake: Season 9, episode 14 "Stronghold": When Bratac has cleared the gate in his alkesh, there is a shot of the gate from nearly side on. There is no wormhole, despite the SGC dialing it less than a minute before.
Other mistake: Carter says that the chance of depositing the heavy element inside the Katow sun while the element is en route is about 1%. However, hypothetically speaking, the actual chances would be infinitely smaller, in fact it would be near impossible. Simply consider the distance from earth stargate to the Katow stargate, the diameter of an average sun, and the time it takes for an object to travel through the gate (about 12 seconds). Taking the closest star to us (Alpha Centruri), at a distance of 4 light years, this means that the wormhole takes ~443ns (0.000000443s) to pass through the sun (using our sun diameter). Similarly, taking the diameter of the Milky Way as the distance to the furthest star in our galaxy, ~100000 light years, meaning the wormhole takes ~17ps (0.000000000017s) to pass through the sun. This means that the SGC would have to shut down the gate within a a maxmium of 443ns or a minimum of 17ps time gap. As we have previously seen, the stargate takes far longer to shutdown than these miniscule time lengths.
Other mistake: Several times, especially in the first season, there is an IDC confirmation on the SGC computer even before the wormhole has been established.
Revealing mistake: When the village canon touches the hot poker to Teal'c's forehead tattoo, the profile view shows that the edge of the applique used by the makeup artist has separated from Chris Judge's face. It apparently was not glued down securely enough, and this is not an isolated incident. It happens quite frequently throughout the entire series.
Factual error: During SG-1's trip across the nation they show a city-scape of Chicago. Which is evident by the Sears Tower. But the Sears Tower was not build in 1969. Construction started in 1970 and completed in 1973.
Continuity mistake: In an early scene "Ma'chello" is lying in the infirmary with a oxygen mask on, it cuts to Frasier and O'Neill talking about him, then cuts back and "Ma'chello" now has nose tubes.
Revealing mistake: When Daniel is talking to the leader of the Tolan, you can see the camera light reflected in his glasses.
Continuity mistake: Season 10 Episode 15: In the scene where Teal'c and his friend are ambushed offworld, he shoots back without first "opening" his staff weapon. After firing back, it is suddenly opened.
Continuity mistake: Jacob Carter repeatedly mentions blending with Selmak 4 years ago, placing it in Series 4 (each season constitutes a year - when Carter leaves the SGC to join Atlantis at the conclusion of season 10, she talks to Teal'c about how they have spent 10 years together). However the blending occurred in Series 2 (6 years ago).
Revealing mistake: Even after Teal'c is dead, you can see in one shot that he is still breathing.
Children of the Gods (1) - S1-E1
Factual error: Carter claims that the gates shift position because of the expansion of the universe. Gravity sources within a galaxy completely compensate for such expansion. The gates would still experience "stellar drift", which is mentioned earlier in the same episode. Stellar drift occurs because stars orbit the galactic center independently.
Continuity mistake: When Jack is revived in the sarcophagus after being caught, the first shot of this his shirt is in perfect condition, but in the next shot of it, there is a knife hole in the shirt which disappears when he is being taken to the "anti-grav torture wall"
Continuity mistake: When Teal'c walks into the Goa'uld force shield on the planet, he is forced off and he almost does a backflip. You can see that he would have hit the floor head/neck first. But when the shot changes, you see him land on the floor sliding on his back, as though someone had just pushing him over.
Emancipation - S1-E4
Character mistake: After trading the pistol for Carter, Jack says "there's only 5 more rounds in that clip." However, the pistol didn't have a clip, it had a magazine, which is completely different. As a member of the Air Force who has been trained in firearms, he would know the difference.
Revealing mistake: When Jack is asking the Martian where he got the idea for the show, you can see the camera light reflected in the Martian's glasses.
The Serpent's Lair (3) - S2-E1
Continuity mistake: When Daniel is shot by a Jaffa staff weapon, the hole in his jacket is very visible. When Daniel comes out healed from the sarcophagus, it has also mended his jacket, but it's shown in other episodes that it doesn't repair clothing.
