Deleted Scene: Part of the final Car Chase took place on an ice rink, with the cars gliding past each other to the accompaniment of Johann Strauss' "The Blue Danube". The scene was cut for timing reasons.
Irony as She Is Cast: This is a movie primarily about cars and driving. Michael Caine couldn't drive at the time the movie was made, and in fact he is never seen driving a car. The only time in the movie that Charlie Croker is assumed to be driving is the cut between when he picks up his Aston Martin at the garage, and in the next shot we see it arrive outside the hotel. But Caine gets out of a stationary Aston Martin after a further cut. Throughout the drive to Turin and the entire heist, Croker is always a passenger.
Throw It In: The scene between Charlie Croker and the garage owner was entirely improvised between Michael Caine and John Clive.
What Could Have Been: Numerous endings were considered. In an interview, Michael Caine said that one was balancing the cliffhanging bus by burning off all the fuel only for the Mafia to turn up and reclaim the gold. Others included the gold being safely transported to Geneva or getting all the way to England, only to be returned to the Mafia as part of a compromise.
A few original lines were later taken out of the movie when the director realized that not many non-Brits would understand them, one regarding "someone from the smokes sticking his bugle in" on Charlie's operation. In American English, the line means that someone was worried that someone else from London would stick his nose into their business.
The screenplay originally was set in London and was to have been a TV show. However the scope of the production was too large for British TV at the time and so the script was purchased for the movie and the setting changed to Turin because it had the most extensive computer-controlled traffic monitoring system in Europe. However Milan had been the original location choice until the producers realized it would be impossible to get a shooting permit.
Liverpudlian pop-star Cilla Black was offered the role of Lorna, however her agent turned it down without her knowledge.
Screenwriter Troy Kennedy-Martin wanted Nicol Williamson for Mr. Bridger, a character he envisioned as "tough as nails" and totally in control of the situation. Director Peter Collinson offered the role to NoŽl Coward instead, which changed the tone of the character.
Coventry does 'a Toronto' - the sewer chase scenes are all filmed in Coventry, which at the time was having its pipes replaced, meaning easy access for filming.