The production had to hire snake wranglers to make sure the areas where they were filming were snake free. Before filming began the wranglers found 25 venomous snakes. The biggest one they found was a 5 foot rattlesnake.
Thomas Brodie-Sangster would put a rock in his shoe so he would remember to limp.
To gain the role of Chuck, actor Blake Cooper continuously campaigned for an audition via twitter. He would send director Wes Ball tweet after tweet after tweet stating that he was made for the role. Wes Ball eventually relented and told Cooper to send his audition to the casting director who stated that Cooper was the perfect Chuck.
The cast spent the week before production participating in survival training in the glade. They learned how to build tools and shelter out of the surrounding nature.
Of the largely British cast, only actor Thomas Brodie-Sangster, who plays Newt, got to keep his accent.