Executive Meddling: Damaged was going to be released nationwide, under an MCA imprint. But the label would have lost money on the record, so they not only wouldn't release it, they filed a legal injunction that prevented Black Flag from releasing any material on another label for several years. This all but killed the band's chances of making it big.
Hey, It's That Guy! - Oh look, future L7 founder Suzi Gardner's contributing backing vocals to Slip It In.
Promoted Fanboy - When the band was performing at a bar, an audience member requested that they play "Clocked In". The band suggested that he sing it himself. He did, and he was good. The current vocalist was looking to switch to guitar to avoid damaging his voice, so the band hired the fan, Henry Rollins, as their official vocalist.
Not quite as "face out of the crowd" as it seems. Rollins had established a friendship with the band prior to this. He talks about it in full in his book Get In The Van.