- Author's Saving Throw: The killer's somewhat lacklustre motive was one of the plot's main criticism (i.e. killing your best friend because he knows about your first marriage to a wife you can't divorce, so that you can marry the girl you love). The murder motive was later revised for the U.S. publication.
- Moral Event Horizon: The killer crossed this with the murder of Babbington at the first cocktail party. Sir Charles murdered one of his friends and/or acquaintances at random just to "rehearse" the main murder.
YMMV / Three Act Tragedy