Possible Clues:

• Results are usually laughable when this missile is launched
• Slapstick missile
• Clown's prop?
• Results are laughable when this missile is launched in panto
• Missile thrown in car dispute?
• It's thrown for laughs, but could create sad picture
• Prude's act I made up for slapstick comedy
• It may be thrown in car dispute that's unsettled
• Director's sweet cast?
• Awfully sad picture of slapstick