User blog comment:The Milkman/End of the Line/@comment-5607673-20120704211317/@comment-1221773-20120704224725

There was only one path that we see. Recall that Anderson mentions the structure they're in is shifting. Shepard may not see anything shifting, but Anderson may have seen it and it brought him to the control room first.

Behind the scenes, though, I think this was the result of a last-minute change. Concept art from The Art of the Mass Effect Universe shows a similar corridor as the one Shepard initially limps down. In the art you can see a figure who resembles Anderson with another who resembles Shepard as they walk down the corridor. It could be that originally, Anderson was in the corridor with Shepard in the game and they reached the control room together. For whatever reason, Anderson was cut out of the scene and his comm dialogue, seemingly incongruous with what the player sees, was added instead.