It isn’t really special, but there’s the bit in Bohemian Rhapsody where Roger Taylor’s high backing vocal is a bit longer than everyone else’s. I’m pretty sure that was a mistake that was left in, possibly because they couldn’t take it out with the tech they had back then.
couldn’t take it out with the tech they had back then.
I’ve heard that they nearly lost the recording because their tape machine had a minor flaw which scraped away some of the tape and which nearly ate the whole tape because of how much multi track overdubbing they were doing.