When I first saw Back To The Future II, as a kid of 15, I didn't realise that Crispin Glover (Michael J. Fox's father George McFly) was not present in the movie but had been replaced by a "double" that was always shot from the back (or upside down) and wore prosthetics in the scenes in which George was acting. In other instances, when they used the footage of the first episode, you can only see the back of Glover. A few years later, when I watched the movie again and noticed his replacement, I found out that he had a "disagreement" (to put it lightly) with the producers/director and that he has been "cut" from the saga.
Yesterday, while I was reading this article, I've stumbled upon the following interview with Glover
In which he explains his version of the story. Apart from the legal and litigation aspects of the story, which do not interest me very much, I was curious about some of Glover's assertion. According to the actor (at circa 1:25 in the video above), also because of his questioning the original ending, some changes were made to the original script of the first episode. Glover goes as far as calling some particulars of the original version of the finale "offending", especially if seen with today's eyes.
Towards the end of the clip (8:20 circa) he also states that, in the original version of the Back To The Future's screenplay, Biff was not supposed to end up as the McFlys subordinate. Glover then ends up the interview joking about the fact that maybe someday he'll "write everything down in a book".
After all the preamble, my question is the following: is there any evidence of any substantial (or not so substantial) changes made to the original screenplay, as stated by Glover? And, if so, what changes were made?