Back to The Future Part III Easter Egg - Pine Tree Mall Reference

Go to the part where Marty is going to go back to the Wild West and is getting information from the Doc at the deserted movie theater. The Doc is explaining to Marty why they are so far away from Hill Valley. The Doc says, "We don't want to risk sending you back into a populated area, or to a spot that's geographically unknown! You don't want to crash into some tree that once existed in the past!", which is a reference to Back to the Future I, when Marty runs over one of the twin pines when he travels back in time, changing the name of the mall from Twin Pine Mall, to Lone Pine Mall.