Writer:	Merrill Markoe, Merrill Markoe, Charles H. Eglee
Director:	Dennis Dugan
Star:	Allyce Beasley (Agnes DiPesto),  Curtis Armstrong (Herbert Quentin Viola (seasons 4 - 5, recurring previously)),  Cybill Shepherd (Madeline "Maddie" Hayes),  Bruce Willis (David Addison Jr.)
Guest Star:	Granville Ames (Man in Elevator),  Francis Coady (Man in Restaurant),  Demi Moore (Woman in Elevator),  Beverly Sanders (Adelaide Sapperman),  Ron Vernan (Seymour Sapperman),  Virginia Madsen (Lorraine Anne "Annie" Charnock),  Jay Goldenberg (Waiter)

Music: "Avalon" by Roxy Music; band plays "Songbird" by Kenny G; "Just My Imagination (Running Away With Me)" by the Temptations; "Cisco Kid" by War; "I Second That Emotion" by Smokey Robinson & the Miracles (edit) As David and Annie stand in front of a video store, a clerk tears down a large "Die Hard" poster featuring a photo of Bruce Willis. (edit) The woman in the elevator with whom David is smitten is played by Demi Moore, who was married to Bruce Willis at the time. (edit)

Maddie (to the therapist): I think I'm over David Addison... (edit)

This episode does not have any trivia. Add some now!

The title is a reference to 1951 science fiction movie When Worlds Collide. The film was based on a novel by Edwin Balmer. It told the story of an out-of-control planet flying into our solar system, and heading for Earth. (edit)