Jay and Brett did back up vocals on their first (self-titled) album. Brett sports a Rancid tattoo on his arm. Matt Freeman said that Stranger Than Fiction was BR's best album. And of course Tim Armstrong sang on Television.
At the Warped show in Cleveland, they were going to play Cease but when Lars from Rancid showed up backstage, Greg said: "Lars is here, looks like we better play what he wants." So then they played What Can You Do? Later when Rancid played, Lars thanked BR and said "Now that's punk rock!".