Originally, Marty was to be a werewolf. Part of the story featured him going all hairy and trying to eat his mother. This element became Teenwolf (1985)
In an early draft of the script, Doc Brown was called Dave and was a rat
The time machine underwent many iterations. In an early draft, it was a mysterious old man who did a special dance.
It is well known that filming commenced with Eric Stoltz in the role of Marty. But did you know that he made the Fly 2, which is one of the worst films I have ever seen?
The effect of the car leaving flames on the road was made by setting fire to stuff on the road. Really.
The effect of the car reaching 88MPh was acheived by driving a DeLorean really fast.
A total of 12 Deloreans were bought as a result of this film - doubling sales.
Lea Thompson, who plays Lorraine Baines, starred in Caroline in the City. Her character was in Friends once which also starred Jennifer Aniston who is married to Brad Pitt who was in Seven with Kevin Spacey from the Usual Suspects.
Director Robert Zemeckis has really big glasses
Steven Spielberg offered to produce this film on condition that it made him lots and lots of money.
The Enchantment Under the Sea dance is a reference to Seven Samurai (1954)
Back to the Future was on TV more in the late 1980s than the Goonies, Batteries Not Included and Jaws put together. Probably.
The name Mcfly is inspired by a poor boyband, who coincidentally invented the time machine in the future and told writer Bob Gale about it.
Back to the Future III was actually written before the first, but it didn't make any sense.
The character of Biff Tannen was inspired by a story Bob Gale read about a character called Biff Tannen.
The Australian version alters the 'Pepsi free' exchange to be a reference to Diet Pepsi and so makes no sense whatsoever.