Revealing mistake: As we know, the watery image of the event horizon is projected onto a blue backdrop. Ger'ak comes through the Stargate and we can see the image of the event horizon, though faint, around and above the Stargate itself and is not confined to normal area for the event horizon. Blatantly visible if you look for it on the airing of the episode on the Sci-Fi network.
Revealing mistake: When Carter says "It will just take a few minutes to initialize" at the super-gate and presses the screen on her hand you can see for a brief second that it is a video recording since the options for play, pause and stop show in the options bar on the screen. (00:36:30)
Stronghold - S9-E14
Revealing mistake: Just after Sam shouts to Mitchell to wait for back up, there is a side shot of a soldier firing a machine gun. There are cases going into the gun without the actual bullet in them, showing they are blanks.
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 ★