Relying on a low budget of $50K, the movie was shot over five nights in a single location with dialogue that was largely improvised.
The actor who plays Amir, Alex Manugian, is also the co-writer. He was essentially "the mole" who helped guide scenes if the actors went astray.
When Kevin (Maury Sterling) tries to leave the house by himself, Em (Emily Baldoni) was given a note to not let him leave and his note was to leave.
Instead of scripts, the actors would each receive only a small paragraph (that only they would see) as their 'goals' for the day. This allowed for the story to unfold naturally and create genuine reactions in the other actors.
The set only had 5 crew members: 2 sound guys, the director of photography, the director, and producer Lene Bausager.
According to Emily Baldoni, after the first mysterious thumping on the "door to nowhere", the actors were both scared and very excited about the story that was unfolding. "Of course we knew we were in good hands, but this is when things got really exciting, because we could see how genius and well-planned everything was. We just didn't have any clue."
Lorene Scafaria (Lee) had the least idea of what movie was being filmed since the rest of the cast had done test footage before. She only knew it was going to be improvised. About the third day of filming, she realized it wasn't supposed to be a big, broad comedy.
Emily Baldoni wanted to immediately bust the box open when it was first discovered. The director, James Ward Byrkit, had to step in since the filmmakers only had one box.
The director, James Ward Byrkit, wanted to use his own house as the setting of the movie. Since his wife was 8-and-a-half months pregnant and wanted a homebirth, she agreed to let him so long as he could do it in 5 days.
Three rental cars were used for the breaking of the glass. The windows were replaced before the cars were returned.
The neighborhood was supposed to look completely dark when the first group visits the other house. It was the same night a Snickers commercial was being filmed in the neighborhood which used huge lights and hundreds of people.
The director, James Ward Byrkit, said the hardest part of directing was keeping everyone quiet since there were so many people who were compelled to speak a lot.
The reason the cameras are so shaky was not so much a stylistic choice as it was giving the actors the freedom to go anywhere they wished to.
There were only two cameras used throughout the filming of the movie except during the dinner scene which had one additional camera.
The filmmakers do not reveal how the comet was filmed other than to say it was a practical effect.
Both sides of the phone call at the beginning of the movie were recorded together, instead of the more common practice of adding in the other side later.
The idea for the story came from wanting to tell a story that takes place only in one room.
The director, James Ward Byrkit, first met Lauren Maher (Laurie) while working on Pirates of the Caribbean: The Curse of the Black Pearl (2003). She played Scarlett, the wench who slaps Johnny Depp.
Test footage was filmed a year prior. The role of Mike's wife (played by Lorene Scafaria) was originally played by the director's wife. She chose not to be in the final film due to being 8-and-a-half months pregnant.
Elizabeth Gracen and Lauren Maher, while enemies in the movie, are great friends in real life.
Lorene Scafaria (Lee) was just finishing writing/directing Seeking a Friend for the End of the World (2012) before filming.
Emily Baldoni's hair at the end of the movie took a long time to appear messed up after sleeping, because it kept falling back into place.
The producer, Lene Bausager, flew out from England specifically to make sure the movie would happen.
Some scenes were reshot six months later. Lorene Scafaria (Lee) changed her hair during this time, so they spent $8,000 getting a wig that matched her original hair. This was as much budget as the entire first shoot.