This is how they lined up:
The botched play
This was a read option. Alex Smith takes the snap and turns to his left where Jamaal Charles is supposed to be. Alex's options at that point -- if the play were run correctly -- were to hand it off to Jamaal or keep it and run it in himself.
But the play was NOT run correctly.
Jamaal went to Alex's right instead of his left. So Alex was left faking a handoff to ... nobody.
Luckily, he quickly recognized the situation -- as if he had any other choice -- and ran it on in.
Andy Reid: "There was probably a little miscommunication there. It worked."
Jamaal Charles: "Yeah, we made that play up (laughs). I went the wrong way. I was moving around and all the formations were moving all day and I just forgot which way to go. My mind went blank, and I'm just glad that Alex was able to execute the play and score."
Alex Smith: Where was Jamaal Charles supposed to go? "[That's] right where he was supposed to go, right where he was supposed to go. It was executed well, the O-line played great up there (laughing)."