Really the entire concept of the Purge deserves to be here. Imagine you lived in a country where every year people are given carte blanche to kill, loot, pillage, and rape to their heart's content. Sure, if you've got the cash you could pay for various means to protect yourself from the yearly slaughterhouse, but not everyone does and some sellers purposely build in flaws to their security systems so you'll get murdered while thinking you were safe the entire time. The government is in on it, there are no emergency services during the Purge so you have no one but yourself and maybe friends and family to help you out (provided they aren't out for your blood), and all of this is perfectly fucking legal and has caused a great economic boon for your nation which gives absolutely no incentive for anything to change. Sweet dreams, folks.
The chipper tone of the New Founding Fathers of America website as it recommends Purge tourism destinations (travel expenses for the Purge are now tax deductible and Portland's human remains powered BioMass Transit is quite the attraction), the best cocktails for your Purge party, and this year's must-have Purge gadgets.
While possibly a minor homage to The Strangers, the home invader who follows Mary around for a solid 10-15 minutes of the film invokes a sense of sheer, unadulterated paranoia that you are being watched, which Mary is clearly feeling. She was right.
The Polite Stranger. Easily the most psychotic character in the film, even more than Grace and the neighbours while maintaining a Affably Evil vibe for the ENTIRE MOVIE.
The news reports of the Purge at the end. One reporter says the streets are covered with bodies. Another man says he saw people walk into an apartment, drag everyone out, and then summarily execute them all in the street.
Mary, having seen her husband die and now being tied up along with her children to be killed, goes from begging for their lives, to resigning herself that they will all die and begging to be able to hold her children one more time before their deaths.