@Reyn,
Thanks, Reyn.
Here is some more interesting trivia about what experts would consider "lost." Some films existed in an original, longer version but were released in theaters in a shorter version. Often, the longer "director's cut" version has gone missing. For example, Vincente Minelli made a three hour version of the musical, On A Clear Day You Can See Forever. The version that was released is only two hours long. The additional scenes are now lost, including a scene where Jack Nicholson sings a duet with Barbara Streisand.