This Back to the Future photo contains
fedora, felt hat, homburg, stetson, trilby, snap brim hat, and campaign hat.
There might also be
cavalier hat, slouch hat, pith hat, pith helmet, sun helmet, topee, and topi.
In the years between I & II, Michael visibly aged and the actress playing his girlfriend was replaced by Elizabeth Shue. To show the closing scene from the first film as the opening of the second, it was necessary to completely reshoot it.