George Lucas wanted to make a Flash Gordon movie but could not obtain the rights so instead, he created Star Wars.
Ronald Reagan was originally announced as the lead for Casablanca. The proclamation turned out to simply be a ruse to keep the actor’s name in the press.
In the movie Dredd, they slowed down a Justin Bieber song by 800 times to create the "slow motion" noise.
George Clooney had a keg of Guinness installed in his dressing room whilst filming Ocean's Eleven.