During the scene where the classmates are in the karaoke bar, one of the students is singing a song that I believe is called "No More Mr. Nice Guy." The words to the song are both in front of him for him to read as well as on a board located directly behind him.

The slip-up comes when the scene cuts to Jon Heder at the other side of the room. The karaoke singer is still visible in the background at a distance along with the words to the song. All the while, you can still hear the music playing to the song, as well as the student's lyrics. The problem is that the words on the board do not match up with the part of the song that you hear him singing.