The car that was used for the car crash scene belonged to Mark Cusack who played the Swat Team Commander. He sold it to the production for £200 - it was then drained of petrol, flipped and scrapped at the end of the shoot.
Filming in the flat was spread across four days - unfortunately for the team it was the hottest week on record in the UK. Fans had to be brought in during shoot breaks when the windows were blacked out.
On a location recce of The Bottle Yard in Bristol which became the set of the facility, the Director Drew Casson climbed up a fence to simulate the moment Cowen arrives. A security guard saw this on CCTV and called the police who arrived moments later as they thought there was a break in.
Director Drew Casson already had a video on his YouTube channel of the Hungerford Town Hall being destroyed by lightning. Producers Miles and Jesse liked it so much they wanted to include a new version of it in the film.