Marty smacking his head after getting hit by car

It's one of the most painful things I have ever seen in a movie, and I have seen Fight Club and Mr. Bean's Holiday.

I know the sound is dubbed in after, but darn it's an effective scene, especially since he hits his head twice.

The only annoying part about it is that Lorraine pointing out the big bruise is wrong, considering where the bump should factually be.

I actually think I saw him doing an interview looooooooooong ago where he mentioned he was getting "twinges" in his hands every now and then even when filming Family Ties and BTTF, not realizing at the time that they were early symptoms of Parkinson's.

It wasn't. Parkinson's disease starts in the brain a good five to ten years before the person starts experiencing obvious physical symptoms. The truth is, Fox would've already had Parkinson's at this time, he just didn't know it.

It wasn't until 1991 when the obvious signs hit him and he got a tremor in one of his hands but even in 1989 on the set of Back To The Future 2 he didn't feel right because he had to re-enact the Johnny B.Goode scene, and he said he felt exhausted even though it was just 4 years later and he was only 28/29. In fact, you can actually see one of his eyes twitching just before his other self hits him with the door when he confronts Biff. Then on Back To The Future 3, he nearly hung himself because he did that stunt himself where Buford tries to hang Marty but his slower/awkward movements meant he mistimed his reaction with the rope.

In his book Lucky Man he talks about how a building in Vancouver was been investigated by scientists where he filmed a show called Leo and Me as a teen. Apparently three other people in Fox's age group who worked with him in that building had also got young onset Parkinson's disease later in life so it was possibly been exposed to certain environmental pollutants such as pesticide.