I met a gal who was part of the SF scene in the Haight in the late 60's she and her husband who was a Bass player for the Isley brothers was briefly in the film.
The murder occurred during the playing of Under My Thumb..The RS after this tour did not play Sympathy For The Devil again until their 75 tour. Jagger said, "The audiences get weird everytime we play that song."
The RS during their Hyde Park Free concert in June of 69 had the English Poof division of the Hells Angles patrolling around the concert. Let me say they were nothing like their American cousins which the RS found out about first hand.
The RS NEVER were the same band after ALtamont, they never played with the same ferocity and intent again. After Altamont they realized that they were entertainers and not out on the fringe of society outlaws. For at Altamont their outlaw image met the asphalt when they ran into some real outlaws in the Hells Angles. Keith Richards after Altamont tried to keep up the image for a few more years by delving into the depths of Heroin.
My favorite scene in the movie is when the RS are playing Under My Thumb and they show a HA looking sideways at Jagger like he was a little f@gg0t and another HA emoting till they physically pulled him aside...In this clip you can hear fear in Jaggers voice.
https://www.youtube.com/watch?v=7mZdvFSiWQI