Found this Reddit post containing a quite considerable number of mistaken sounds left on songs.
Here are some examples of what can be found on this link:
John Bonham - Since I've Been Loving You
John Bonham's squeaky kick drum pedal in "Since I've Been Loving You"
The Beatles - Hey Jude
In the Beatles, Hey Jude, at 2:59 of the song, someone can allegedly be heard to say, "F****ng hell!"
Metallica - Master of Puppets
In the Master of Puppets' (Metallica) solo, there's an accidental note that Kirk Hammett says he's hardly been able to replicate since. He accidentally bent the string off the fretboard.
The Rolling Stones - Satisfaction
Rolling Stones - Satisfaction - Toward the end in the "and I try, and
I try, I can't get no" part, Keith cuts in too early with the first
note of the guitar riff. It's just a quick buzz of the guitar and then
he stops it when he realizes it's the wrong time.
Source: Just listen to this part in both the studio version and a live concert
B-52 - Love Shack
"TIIIIIIINNN ROOF! Rusted." from the B-52s' "Love Shack" was a mistake. It was originally supposed to be the start of a new verse or bridge or something, and Cindy Wilson came in singing it during recording, not realizing they were stopping where they were and recording that bit later.
Also, I know of a laughing at the end of the song Radio, recorded by Cash Cash for their debut álbum Take it to the Floor, but I can't tell wether it's left on purpose or not.