The family and I are huge Back to the Future fans and must have watched them all a good few hundred times... each.
Sometimes it's a little strange and annoying when cast members either leave an ongoing movie series or trilogy or of course pass away and another actor has to replace them to keep the continuity of the story intact. One such occurrence was when original Jennifer, Claudia Wells, left the production before the second movie and Elisabeth Shue replaced her (not for the better in our minds).
This video below shows you the ending of the first movie (with Claudia Wells), where the Doc comes back from 2015 to grab the couple and whisk them off to sort out their kids, alongside the second movie beginning where we see the same event but with Miss Shue. Obviously director Robert Zemeckis wanted the two scenes to be as close to each other as possible and when you watch the vid you'll see just how close he came. It's a shame it wasn't 100% spot on but still, it's actually pretty spooky...
Enjoy!