These stills provide a great look at Megatron and seem to show him taking a few blasts to the chest and head complete with fire flare-up. The future doesn't look too bright for the villain. Thanks to InvisbleMan for the pictures.
Here is a close-up of a moment in the field where Optimus Prime goes flying from a kick by Megatron. In the background is three Transformers many are assuming to be Blackout and Starscream. As the picture from Andrew (thanks!) shows, the arms, shoulders don't quit match. Maybe Starscream taking on a rather odd pose (I think supposed appear to be stalking) or a different character all together?