In the slow motion scene at the end when Peter reaches out for Alicia's hand entering the press conference, David Dworetzky (the editor) accidentally inverted the shot, left to right, in his edit. The shot appears to be of Peter's left hand and Alicia's right (putting Alicia on Peter's left as they walk in the room). But the hands show no ring on Peter's left ring finger, and a wedding ring on Alicia's right ring finger. The next shot is of them walking in with Alicia on Peter's right, opposite of the previous inverted shot. Subsequent shots (Peter leaving the podium and Alicia grabbing her face after being slapped) show both Peter and Alicia are wearing their wedding rings on their left ring fingers.
At 39:28, as Alicia and Peter walk out to the press corps, they are holding hands, visibly showing her wedding ring set on her right hand. After Diane slaps her (a few minutes later), her wedding ring set is clearly on her left hand. For that matter, the entire shot is likely flipped, as she walks to Peter's left, hand in hand, but when they exit the doors, she's on the right, still holding hands.