Researching documented cases for a small independent project. The classics: - The cough on Pink Floyd's 'Money' (Roger Waters) - John Bonham's hi-hat dropping on 'The Song Remains the Same', they kept the count-in - Cliff Burton's bass tone on 'Master of Puppets' being slightly out of phase on one section - 'I've got blisters on my fingers!' on Helter Skelter (mono mix only)

What other mistakes are documented (Mojo, Rolling Stone, biography, engineer interview) that ended up shaping the album more than the producer planned? Especially interested in cases where the engineer / producer has actually said on record 'we kept this in because of {specific reason}' rather than fan theories.