There's an interesting theory that Nijinsky staged the riot. Of course there's no proof, but some hints that he might have done so:
-Sacre didn't cause any riots in other places it premiered
-Although Sacre is often considered to be the first modern piece of music, it really wasn't
-there were numerous hooligans and rioters in the audience
-Nijinski "calmed" the audience by flicking the lights on and off repeatedly
-Nijinski was overheard exclaiming it's "exactly what I wanted".
There's another interesting theory that the riots were actually caused by the choreography. As opposed to what is common in ballet, the dancers turned their feet inwards.
http://www.youtube.com/watch?v=jF1OQkHybEQReconstruction of the original ballet: with similar backdrop, reconstructed costumes, make-up and choreography.