My mum said the movie ended like that because the media in those days couldn't (wouldn't) show bad guys getting away with criminal activities. However:
The mystery of The Italian Job's cliff-hanger has been resolved after almost 40 years by Sir Michael Caine.
The 1969 film ends with a gang of gold thieves hanging over a ravine in a bus. Every step they take towards the loot threatens to tip them into the abyss.
"Hang on lads, I've got a great idea," says Sir Michael's character, Charlie Croker... and then the credits roll.
The star says he would have saved them by "switching on the engine", burning off petrol until it righted itself.
"I crawl up, switch on the engine and stay there for four hours until all the petrol runs out," he said.
"The van bounces back up so we can all get out, but then the gold goes over."
"There are a load of Corsican Mafia at the bottom watching the whole thing with binoculars. They grab the gold, and then the sequel is us chasing it."
Sir Michael first revealed his version of the events in a BBC One documentary marking his 70th birthday, but gave fuller details at the 2008 Visit London Awards this week - where he was named London's favourite Londoner.
He even suggested that the alternative ending had been filmed in 1969, but producers later decided against using it.
His disclosure comes as the Royal Society of Chemistry (RSC) holds a competition to find the most original, and plausible ending to the film.
Dr Richard Pike, chief executive of the RSC, told BBC Radio 4's Today programme that Sir Michael's explanation was just "one of those many plausible routes to securing all that gold".
"I guess what we're looking for are the detailed calculations to show that, if you were to burn all that petrol off, would it be sufficient to allow the coach to balance?"
Dr Pike added that almost 1,000 entries had been received for the competition, despite the stipulation that "the judges will not accept any solutions that involve the employment of a helicopter".
"Beyond Michael Caine's own proposal, which a number of people have put in, others have suggested jumping out of the bus and going down and getting the gold," he said.
"Others have suggested superconductivity and the use of magnetism - although some people have pointed out, quite rightly, that gold is not magnetic.
"Other options involve even melting the gold, using the burning of the petrol, and in a sense sucking the liquid gold towards the fugitives."
The competition winner will be revealed on 8 January 2009.
Its aim is to promote greater understanding of science, and to highlight the 100th anniversary of the periodic table, of which gold is one of the 117 elements.