Grammar issues? I don't have any. : p I know when I posted my edit here (in the comment) lyricsmode took down some capitalization for some reason, but there were more grammar errors in the version that was up that I edited. I'm picky about that, so I'm pretty sure any 'errors' were written into the song.
The mistake that irritates me the most is the line where taeyeon says 'they'll be watching me. ' 'probably watching me' is absolutely wrong. That sounds ridiculous.