During the airport scene, actress Mary Lindberg's parents sit behind her, and actor Joe Belknap's parents walk behind him. As the filmmakers decided, the Lindbergs await the Belknaps arrival, and leave the airport together.
The TV station Charlie turns on is Channel 19 WTDT. The number, call letters, and logo are all in reference to Stephen Kings' Dark Tower series. 19 is an important, reoccurring number, TDT stands for The Dark Tower, and the logo is a variation of the Eye of the Crimson King symbol.
The large snowfall on day three of production forced the cast and crew to abandon a location in the middle of a scene, only to seek shelter at a gas station in Fisk, WI for over two hours. During this time, the cast and crew entertained themselves while producer Lee Marohn attempted to secure a new shooting location and co-writers/directors Adam Bartlett and John Pata rewrote the script to adjust to the weather.
Actors Steve Herson and Cheri Sadlin, who played the married couple Harrison and Ellen, never met before arriving on set. However, the two had "phone dates" and exchanged multiple emails to develop the characters and their relationship.
Production wrapped in just under eleven days. The post-apocalyptic narrative was filmed over the course of seven consecutive days in April of 2011, while the flashbacks were shot in three and a half consecutive days in August.
The present timeline was filmed in chronological order, a decision that ultimately saved the production as a heavy snowfall on the third day caused for drastic rewrites to include the sudden change in weather.
To achieve a visual difference between the two timelines, the present timeline was shot in April, giving it a post-apocalyptic feel due to the trees being bare and the grass dull from the winter. The flashbacks were shot in the middle of summer while everything was in full bloom.
The cast and crew refer to the production as a "trial of the elements." On the first day of production, they had to battle gale force winds while standing in an open field. The second day consisted of sitting around a campfire for five hours, while everyone struggled inhaling the smoke and keeping it out of their eyes. The third day brought an unexpected blizzard, producing over ten inches of snow in a matter of hours. The snow began to melt as temperatures rose on the fourth day, as the production moved to a fully functional farm, and were standing ankle deep in slush and manure.
Co-writers Bartlett and Pata wrote every word of the script together. For sixteen months, they met every Tuesday and Thursday, for anywhere from four to ten hours at a time, and drank endless amounts of tea while writing.
In the opening of the film, Charlie is seen eating cereal and reading a comic book, which happens to be Fear Agent, co-created and illustrated by Tony Moore, who also illustrated variant artwork for the film.