Ricky Manson asked Emily Owen to slap him for real. After four takes the director decided he liked the first one the best.
It took over 20 attempts to drop the USB stick to the ground floor.
The scene where Clive is trying to beat the others down to the lobby was done in one take.
The final shot caused some of the cast to experience vertigo.
Beth Arthur volunteered for the role as dead Janie.