Some observations of mine from the photos:
1. The lead car has debris on the roof above the cab area, in the form of either soil, or vegetation, or both, in addition to scrape marks on the side facing the Hudson River, indicating it likely turned over and then righted itself from the forces generated in the accident; such a maneuver would indeed create violent motions sufficient to throw passengers out.
2. Had it gone off the tracks a little further, the station would have been hit and the carnage factor way up, with people on the platform getting wiped out and rail cars deformed similar in the way the German ICE was, from hitting a hard stationary object.
3. Not accident related, but interesting, is a photo revealing the long dormant south track (Spuyten Duyvel used to be a wye configuration) that would enable traffic to run from the bridge to southbound. Old printed materials I have state that the need for such movements were rare, and so the track was taken up, except for a few feet shown in the picture.
This is a big downer, and I feel bad for the losses involved and the effects it shall have in many areas, causing more uncertainty, distress, grieving, and sadness.