Whilst the movie was filmed in 2015 the panoramic shot of central London containing the 'Gherkin' also shows the old building at 20 Fenchurch Street, which was demolished in 2008, its replacement, the 'Walkie Talkie' was completed in 2014.
The goof item below may give away important plot points.
Incorrectly regarded as goofs
The feral children wearing clothes despite growing up outside civilization without parents is not a plot hole. They're intelligent beings who live in a library full of pictures of people and have seen thousands of zombified adults. And presumably they still need to protect themselves from the elements.