Revealing: When they are escaping in the beginning of the episode, watch Rodney dial. As he finishes, one of the DHD address panels pops out and falls off.
Continuity: When the Atlantis team finds out that the experiment has caused problems in another universe, McKay's sister says to Rodney, something like,"You said that the chances of connecting to another universe that was inhabited were astronomically small." It was in fact Carter that said that.
Audio problem: McKay is talking to Sheppard about the differences between himself and Rod, and at one point says that maybe Rod screwed up and was chosen for "a one-way ticket to another universe", yet his lips form the word 'galaxy'.
Factual error: When Dr. Weir is distracting the scientist by talking about World of Warcraft, he says that he has a level 75 character. The maximum character level is 60 at the moment, and 70 with the forthcoming expansion pack. Not a character mistake, as he clearly knows enough about the game.
Continuity: After returning from the Daedalus, McKay talks to Nola about how he had been a god to them the past years. In the shots filmed from his front, the standard radio headset is visible in his ear. In the shots from behind, it is gone.