Some of the aerial footage was shot by a second unit in the ghost town of Prypjat, near Chernobyl, in Ukraine. Director Colm McCarthy: "I was very interested in post-apocalyptic imagery and urban exploration. We wanted to surprise people rather than have people coming in expecting a studio level film. We sent a micro drone unit to Pripyat, Chernobyl to shoot helicopter footage with Pripyat doubling for urban London." 
Glenn Close's sister-in-law, Deb Close, is a massive fan of zombie films, having always wanted to be in one, and has a small role as one of the "hungries" in the scene where the group has to work their way through a crowd of them. She is the one wearing a blue knit, with green facial fungus and blood around the mouth and neck, that Glenn stares at as her character walks past. Deb flew to the UK especially for the part, and the first thing Glenn did after accepting her role was call to let Deb know she was in a zombie film.
The film shares similar themes and plot points to the PS4 video game the Last of Us. Both feature a fungal zombie plague, both have a last stage of infection where people sprout spore pods, both zombies overwhelming rely on a single sense (smell and sound respectively) meaning the heroes can move from hordes, both feature a young girl who potentially has the cure who needs to be moved through the infected zone, both focus on her relationship with a gruff reluctant father figure. The similarities were highlighted in several reviews.
According to director Colm McCarthy an influence on the style was Gareth Edwards's Monsters (2010): "I also spoke to Gareth Edwards about "Monsters" ahead of shoot. That film was a reference point." 
In the book, Helen Justineau is described as a dark-skinned black woman in her 40's. Miss Justineau's dark skin is also a draw for Melanie, as the character states more than once in the book. Melanie also considers her teacher the most beautiful woman in the world. An excerpt from the book says; 'Although Miss Justineau's face stands out anyway because it's such a wonderful, wonderful colour. It's dark brown, like the wood of the trees in Melanie's rainforest picture whose seeds only grow out of the ashes of a bushfire, or like the coffee that Miss Justineau pours out of her flask into her cup at break time. Except it's darker and richer than either of those things, with lots of other colours mixed in, so there isn't anything you can really compare it to'. A short story written by Melanie in class describes Miss Justineau's general appearance: "Once upon a time there was a very beautiful woman. The most beautiful and kind and clever and amazing woman in all the world. She was tall and not bent over, with skin so dark she was like her own shadow, and long black hair that curled around so much it made you dizzy to look at her". Gemma Arterton, who is white, was cast for the role. She was in her late 20's when the film was shot.
Filming for the movie was also shot at RAF Upper Heyford in Oxfordshire. In the book the actual location is an RAF base in Bedfordshire. To make these scenes more authentic to the book an actual real family from the book location was cast to play a family of infected 'Hungries'. Actors and Special Action Artists Pete Buzzsaw Holland, Tina Holland and their son Zak Holland were cast to work side by side with the stunt team in scenes along with the main cast. Over the duration of the location shoot the Holland's became affectionately referred to as 'The Hungry Family' by their fellow supporting artists and it has now become a title that has stuck and 'The Hungry Family' are proud to be known by.
The trivia item below may give away important plot points.
There is a real-life fungus that bears a remarkable resemblance to the one described in the movie. The O.unilateralis, or zombie fungus, thankfully only infects carpenter ants. When the ants are first infected they undergo severe whole body convulsions (as seen in the human hosts of the movie). The fungus then starts controlling their brain. Eventually, the zombie fungus directs the ant to climb up a tree where the 'next stage of the fungus' life cycle' occurs. Specifically, as seen in the movie, the fungus grows through the victim's head to produce a long stalk; when the conditions are right, pods open to make the fungus airborne, allowing it to infect many more hosts. Interestingly, the ant zombie fungus also protects its infected host from some environmental pathogens, as also seen with Melanie's symbiote.