Director James DeMonaco was asked why the film began with footage of multiple purges taking place outdoors - yet he opted to have all purging occur inside one family's home. He responded, "we only had 19 days to shoot and $2.7 million to work with". If he ever got a chance to do a second one, he vowed it would be more like Escape from New York (1981).

According to director James DeMonaco, the famous road-rage incident awakening the idea for The Purge happened like this: He and his wife were driving on the freeway when a drunk driver cut them off nearly killing them. After both cars stopped, the other driver's lack of remorse enraged DeMonaco enough to engage in a fistfight and police eventually had to get involved. After the incident was over, DeMonaco's wife turned to him and commented how great it would be to have one free murder a year. He felt bad admitting this because she's normally a "sweet woman".

The homicidal ladies in white dresses were based on Charles Manson's killer/followers. Director James DeMonaco claims obsession with Manson from an early age.

James DeMonaco, director and writer of the film, got the idea for the story after his wife made a remark about an episode he had with road rage.

On the prospect of a real Purge, director James DeMonaco once said "...honestly I'd probably just go to Canada and hide."

Over one hundred different masks were considered for the freaks.

This movie was also turned into an extreme walk-through horror maze/experience in Los Angeles called "The Purge: Fear the Night."

In all 3 purge films there is a character named Sabien. He or she is usually reffered by Mrs. or Mr. Sabien, yet all 3 films are in different locations.

The film was turned into a scare zone at Halloween Horror Nights 2013 at Universal Studios Hollywood.

Rhys Wakefield was cast as the Polite Leader of the home invaders one day before shooting started. Several casting sessions had been held, but all the other actors who had auditioned had overdone the part. According to James DeMonaco, Wakefield played it cool with an unsettling smile, as if he had fun with it, which was perfect for the role because it reminded DeMonaco of the cult dynamics of Charles Manson.

Ethan Hawke is an old friend of producer Jason Blum and director James DeMonaco, and was happy to appear in The Purge to give their low-budget movie some star-power. As usual in Blum's productions, cast and crew work for scale and receive a percentage of the profits, if any. Hawke reportedly received only $3000 upfront, but due to the movie's worldwide success and the back-end profits, he has probably received more money for this film than for any other in his career.

The purpose of the masks was for them to resemble Halloween masks, a metaphor for the fact that some people see the Purge as a holiday of celebration.

Zoey (Adelaide Kane) states that her dad does not like her boyfriend, Henry (Tony Oller), because he is older. In real life, Kane is older than Oller by a year.

Writer/director James DeMonaco has a deep fear of firearms, and channeled that fear into the movie, stating that traditional villains are much less scary now that random people carrying guns can cause a massacre everywhere: "I'm terrified for my country. So I think that cynicism seeps into the film. America itself becomes the canvas, instead of the haunted house, the canvas is America. We don't need ghosts or vampires anymore when we're just killing each other, you know?"

There are six sirens when opening Purge at 7 PM March 21st and seven sirens when closing Purge at 7 AM March 22nd.

Yuli Daniel wrote a similar story in a short novel called "This is Moscow Speaking." Under Nikita Khrushchev's rule, dissidents like Daniel had some limited freedom to write stories critical of the Soviet government. However, this ended when Leonid Brezhnev came to power, and in 1965, Daniel was arrested and tried along with companion Andrei Sinayevskii, for writing "This is Moscow Speaking," among other stories he wrote, in the first show trial since Stalin's Purge. Early the next year, Daniel and Sinayevskii were found guilty and sent to a labor camp in Siberia. This marked the end of the freedom of the dissidents' movement in the USSR.

After several successful runs as a scare zone at Halloween Horror Nights in Orlando, FL, the movie was turned into a full scare maze for the 25th Halloween Horror Nights in 2015.

The Security System code is 101382.

In the trailer, the voice of the Emergency Broadcast System is male. In the movie the voice is female.

The total number of freaks at the Sandins' door is eight (until reinforcements arrive).

The film takes place in 2022.

In Spain, all the trilogy have different titles but the same subtitle to identify it: -The Purge: La Noche de las bestias (The Purge: Night of the Beasts) (2013). -Anarchy: La Noche de las bestias (Anarchy: Night of the Beasts) (2014). -Election: La Noche de las bestias (Election: Night of the Beasts) (2016).

According to timeanddate.com, sunset on March 21st, 2022 in Los Angeles, occurs at 7:06 PM, while sunrise on the following morning occurs at 6:54 AM. The daylight length of the 21st: 12 hrs, 10 min, and 24 sec. The Purge is from March 21, 7:00 PM-March 22, 7:00 AM (12 hours). Also, March 21, 2022 is a Monday.

At the very beginning of the movie, when James Sandin arrives home, he says, "Home again, home again, jiggety-jig." This is from the opening of an old nursery rhyme, "To market, to market, to buy a fat pig/Home again, home again, jiggety-jig."

The actresses Lena Headey and Adelaide Kane (Mary & Zoey Sandin, respectively) both play queens on separate shows. Headey as Queen Cersei in Game of Thrones (2011) and Kane as Mary Queen of Scots in Reign (2013).

Ethan Hawke previously worked with director James DeMonaco on Little New York (2009).

Lena Headey and Ethan Hawke who play a married couple in this film previously appeared in Waterland (1992) 21 years earlier, though they shared no scenes together.

In one scene, Mary is startled by her son's half melted toy robot. Lena Headey (Mary) had starred in Terminator: The Sarah Connor Chronicles (2008).

The purge is held every year on March 21st. If you write out the date in numeric form, it coincidently is 03-21. Or, 3...2...1 which is also signifying a count down.

Director James DeMonaco never thought the story of the boyfriend attempting to kill the father meshed very well with the rest of the story. Originally, it was supposed to be the daughter trying to kill the father. The studio refused to allow it, so the boyfriend was a rewrite.

During the 5-minute climactic scene where the neighbors begin to purge, one subtle detail making Mrs. Grace Ferrin particularly menacing is that she never blinks while directly addressing her victim. Whether smiling or not, the wide-eyed entranced glare indicates psychological detachment.

The Bloody Stranger, later identified as Dante Bishop in the third Purge movie (played by Edwin Hodge each time) is the only person to appear in the first three Purge movies.

The house is located at 11841 Iverson Road in Chatsworth, California.

First and final appearance of the Sandin family and The Freaks.