Joaquin Phoenix made a wooden walking stick for Bryce Dallas Howard during the 19th-century preparation the actors participated in before the film. He engraved the name of her character, Ivy, on the walking stick.
M. Night Shyamalan initially had a different concept for the "those we do not speak of" creatures. They were originally conceived to be monsters similar to the rock drawings featured in the movie trailers: similar to lions walking on their hind feet, complete with shaggy manes. When the creatures were built to full scale and brought on set, Shyamalan felt that the design was completely unbelievable. The creatures were quickly redesigned, most noticeably with the addition of the red cloak.
Edward and Tabitha Walker actually have five daughters. Kitty and Ivy are the oldest. When Ivy is singing to Kitty Edward and Tabitha are watching from the doorway. Edward is holding one daughter, Tabitha is holding another, and the third is standing between them. The three girls can also be seen during the raid on the village by the creatures. When they are in the cellar, Kitty is holding the baby and the other two are nearby.
Local Chadds Ford artist Andrew Wyeth's works were used as inspiration for the look of the film. In fact the house shared by Joaquin Phoenix and Sigourney Weaver was a copy of the one that appears in a Wyeth watercolor painting titled "Open Shed".
The trivia items below may give away important plot points.
The film has a number of similarities to the young adult book 'Running Out of Time'. The book is about a village where the people who live in it think they're living in the 1800s, when actually its set in the present day. The heroine of the book also goes searching for medical supplies, and the village elders take steps to make sure their children never learn the truth of their world. The book's author, Margaret Peterson Haddix, threatened to sue for plagiarism; M. Night Shyamalan wrote off the similarities as "meritless."
According to Steve Boeddeker, the MPAA gave the film an "R" rating due to a single sound effect, which was later removed. It was the sound of the knife stabbing Lucius. Boeddeker has stated that the scene worked even better without it.
Production almost had to shut down because it started snowing, with 14 inches of accumulation, but during the night it rained and all the snow melted. Soon after, they dug the hole that Noah falls into, which is why it looks so muddy.
M. Night Shyamalan:
The newspaper that Jay the guard (Shyamalan) is reading at the end, is The Philadelphia Inquirer, which proposes the story is set in Philadelphia, as are all other Shyamalan movies.
On the night the creatures come into the village Ivy tells Lucius that she and Kitty are watching the younger children (their little sisters). Noah is also with them. It is likely that the Walker and Percy parents were acting as the creatures that night.
M. Night Shyamalan:
When Kevin the security guard is getting the medicine from the cabinet, the guard he is talking to is reflected in the glass, the guard is actually writer/director Shyamalan, he is never shown other than this reflection.
Although the tombstone reads 1897, it is actually taking place during modern times, as noticed when Ivy climbs outside of the wall. The original villagers probably choose a year that they figured was great for starting a village with intended innocents.