The Olympic Flag was carried out of the stadium by eight of Norway's best summer and winter athletes of the past then.

As for the singing of the Olympic Hymn itself, it was sung by Sissel Kyrkjebø. Her Olympic Hymn rendition, in NORWEGIAN, is considered one of the best performances of it ever. On top of that, she sings the beginning part of it in "a cappella." It is a musical term that means she sings without any music to accompany her, like you hear with some church hymn music. That, in itself, is much more difficult than most people realize. She is still a singer today.

As for the way the Olympic Flag made its exit, it was quite a show. You will not see it like that often in a closing ceremony. Also, it was "upside-down" if you know what I mean. (less info)