“Ultimate Guitar” has a list of songs with mistakes made during the recording that were kept in the songs, because somebody liked them. There are seven on the list but here are the classic rock ones:
“Roxanne”, The Police. At the beginning, you can hear a cluster of keyboard notes followed by Sting’s laugh. He accidentally sat on a keyboard. It’s about four seconds into the song.
Led Zeppelin’s “Black Country Woman”: They were recording at a house, and just as they started, a plane flew overhead. They decided to leave the plane noise in. You can even hear Robert Plant saying, “Nah, leave it.” Catch it at the very beginning.
“Wish You Were Here”, Pink Floyd. David Gilmour coughs and can be heard breathing right before the main guitar comes in. Rumor has it that he couldn’t hold in a cough due to his heavy smoking and he was so upset when he heard the final take that he quit cold turkey the following day. The cough is about 27 seconds into the song.
Check out the full list here.