I think you might be right. The high-def version makes it easier to see where shadows fall. It looks like it's the back section that's separate from the rest. If you watch the high-def closely it looks very much like the first 3 segments of the track are behind the last segment (notice how his shadow passes over the last segment THEN the first 3 segments):
Ya, if you watch it carefully you can see it burp a few times when the water moves past that post.
EDIT: I made a diff in GIMP of the shadow. It looks like both the top and bottom left facing ledges are connected. Notice the hard edges between the adjacent pillars.
http://www.youtube.com/watch?v=0v2xnl6LwJE#t=33s
http://imgur.com/c1Plc