Alfie Gladstone, was originally written as a girl - Sarah Gladstone - until James Peverill struggled to cast a girl so his friend from work allowed her son to play the role.
The name Gladstone is taken from The Graduate (1967). Dustin Hoffman's character uses the fake name - Mr Gladstone - when checking into the hotel. A line from The Graduate is also used when Nolan speaks to Bradley for the first time - "Mr Gladstone, how are you this evening?"
The 1st draft of the script was titled 'The Man Who Knew Nothing' and was going to be a Hitchcock style thriller.
In an early version of the script, Bradley Gladstone said that he worked for 'Universal Export' - the company that James Bond pretends to work for.
In Gladstone's House, the television is on a movie channel and shows Power Rangers. James Peverill has stated that he has always wanted to do a Power Rangers reboot movie.