ILM's VistaGlide was created for Back to the Future II to enable actors to be doubled and play against themselves in scenes.
With such a well-wrapped story, making room for a sequel wasn’t exactly easy – and even the film’s director, Robert Zemeckis, talked about this in the 2002 Back to the Future Part II DVD ...
Director Robert Zemeckis took a unique approach to the making of the Back to the Future sequels, and he ended up having a major regret over it.