During the first photo shoot Rowdy is present too.
In the second photo shoot, director Bill Lawrence is visible in the close up when Carla and the Janitor are speaking (he's on the top row above Carla's left shoulder), but then he appears laying down on the ground in front when the camera pans out as the photo is about to be taken.
While Dr. Kelso says he is 57, Ken Jenkins, the actor who portrays him, was 65 at the time. Michael Learned, the terminal patient, is only a year older.
Dr. Kelso mentions that he is 57. Given that the photo is for year 2005, this will put his year of birth to be 1948.