Just a small detail, but I wonder why they needed to re-do Martys Johnny B Goode solo.
The solo is similar to the original enough. It hits some of the same signature parts and obviously the spliced-in orginal moments are seamless.
But it's definitely played differently.
They needed to show Marty from different camera angles
Funny thing, during "making of" publicity, I recall Michael J Fox talking about the 1985 guitar solo and how he couldn't believe he (the actor) could actually pull off all the "stunts" he'd done in the first film
I thought it was odd that he aged THAT much in only four years
Now we know the truth -- it wasn't age so much as his disease catching up with him
What I mean is, the solo itself is played differently between the two. They didn't need to re-record the solo at all. They still had the audio from the original. MJF would only need to pantomime the original solo, which he did anyway. It's not like MJF played it live.
shareCould have to do with copyright over the specific performance by whomever played it the first time
There's also a notion in moviemaking, which I personally disagree with, that it's better to be internally consistent than duplicate something externally
In this case, since some of the solo had to be redone (to extend it), Zemeckis may have thought it'd be better to just redo the whole solo
The same logic was applied in "Total Recall," where the Kuato puppet was shown protruding from an obvious puppet version of his brother George. The same puppet, with full functionality, was fitted onto the actor Marshall Bell, but Verhoeven thought it looked more internally consistent for both Kuato and George to be puppets in that scene.
Like I said, it's a thing. But I generally disagree with it