Timeline Observation
So, at the end of part3, Marty ends up in the 4th version of 1985?
I) Beginning of part 1 - George is a loser
II) End of part 1 - George is successful/Marty has a car accident/Ravine is called Clayton
III) Middle of part 2 - Biff is a millionaire
IV) End of part 3 - George is successful/Marty doesn't have an accident/Ravine is named Eastwood