All throughtout the song..esp chorus and the second verses and second chorus..theres Airy gibberish sounds on the background..Alex the Kid.. delete it....
I don't think she did, but that technician did an awful job of editing ha vocals there Once I noticed it I just do a count down in my head to the "tddDD"
Sonic Youth recorded the entirety of Experimental Jet Set, Trash and No Star over the same tapes as their album Sister, so when it gets quiet you can hear Sister playing in the background.
I doubt it's a mistake (probably just a similar noise) but I always think they accidentally recorded the AIM notification sound in Gwen's Early Winter There's a weird background noise towards the end. I always used to think I was getting IMs until I realized it was part of the song.
There's really a light glitch sound 
You have to put the volume not too low tho.
delete it....
literally ruins the song