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)
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)