After all the credits are done rolling Mike Dexter yells out "I'll kick everyone's ass in this room" which he said earlier on in the film.
Yearbook photos of all the characters in the movie are shown as the end credits roll.
William's two friends are walking along a street discusing that missing the party was no big deal when a UFO shadow appears on them (like the one in ID4) and they are abducted by it
Candid party photos of the characters in the movie are shown as the end credits roll.