While it looked great on film, both Oregon shoot days had constant rain with very few minutes of dry weather to shoot certain scenes; this at times caused Rebecca Hodge who portrayed older Ellie to be quite cold due to her character being the only one without a jacket.
Emilie Westover who portrayed the Clicker in the film was actually blinded by the clicker mask and had to be guided back and forth around set as much of it was shot in the forest.
Amy Kay who portrayed younger Ellie was cast after being found on YouTube for an Ellie cosplay and role play.
During the scene where Ellie sings to Dina around the campfire, a fire was not allowed to be built on location so it was replicated with a color changing LED light while a production assistant made flickering motions in front of the light.