Olivia Colman was offered a key role.
Harry Kane was a character in this film. There also happens to be a well known footballer with the same name.
The external, and most internal, shots of the theatre on Jersey, where the final of the Magic Shield competition is held, were shot at the Theatre Royal in Nottingham. Many of the theatre's ushers were recruited as extras to play ushers in the film.
The idea of Harry making a Pros and Cons list about his girlfriend and being found out is inspired by an episode of Friends where Ross makes a Pros and Cons list about Rachel and is found out.
Whilst filming in Nottingham, unit signs being used in the film were repeatedly being stolen by teenagers as they had the word "magic" on them. Multiple signs had to be ordered, at £3 each.