Sagan had a double puncture with about 40 to go and seemed to have a bit of a problem with his brakes/gears(?) after the changeout, but was paced back in by half the Cannondale team so that probably had no impact.
Cav had an untelevised off from about 30 out, so no-one saw exactly what happened. Didn't appear too serious as he more or less paced himself back into it and bunny-hopped a roundabout on the way through.
The pack kept a stupidly high pace on throughout so getting back on may have cost them a bit from the tank, but to my untrained eye it was all technical; OPQS and Cannondale's trains tried to control it from too far out, got swamped and unseated after the 5 (initially by Argos-Shimano), and consequently both Cav and Sagan were left to solo it, whereas Lotto timed it just right with Henderson/Greipel.
Edit, or what laurence said. Damn phone calls interrupting my posting.