One Left
The waitress at the diner believes that Mickey and Mallory will leave her alive as it's between killing her and a man. Ironically, the couple is impartial to whom they kill and Mickey takes the woman's life.
False Impression
The hillbillies in the opening scene believe that Mallory will sleep with them as she dances wild and seductively to them. Ironically, she's luring them in for the kill--literally, as she and Mickey take their lives.
Gale
Gale is murdered in the end, and he stretches his arms out before Mickey and Mallory shoot him. This is a symbol that Gale believes himself to be a martyr, dying willingly as the reporter who brought the world the "natural born killers". Ironically, he's not a martyr, but the fool who chose to trust two lunatics on a killing spree.
Riot
A riot erupts in the prison where Mickey and Mallory were held during the couple's post-Super Bowl interview where they dub themselves natural born killers. Ironically, this riot only happens because it is given a platform by the media.
Family
Mickey and Mallory are seen with two kids at the end of the film. The irony is that they appear to be a normal family, when in truth they are violent killers that seem to be preparing to groom the next generation of violence.
