another fix mentioned plenty of times before is how little you really used the inventory.
it was lacking a lot compared to pretty much all the other recent telltale games. so heres a couple suggestions...
i would like to see you be able to combine things and puzzles that involve using multiple things in the inventory, but bttf doesnt even give us that option. just simple things like "put the gum on the stick" tasks can spice up a puzzle. (vague example, i think the game that popped into my head was beavis and butthead virtual stupidity... great, stupid adventure game :-) )
and also, i'd like to be able to pick up some things that dont necessarily effect the storyline, but would add some nice dialogue. the one example i have for that would be at doc estate sale, you see his "mind reading" helmet device. i'd like to be able to have that in the inventory to be able to use on random characters and see what they are thinking, like biff would be one thats bound to have some funny/evil random thoughts. (although i guess stabbing random people in the face with that plunger might not go over too well with most people... :-P )
Why are things so heavy in the future? Is there something wrong with the earths gravitational pull??