30 years ago next week, Dr. Emmett Brown arrived from the future to pick up his friend. Together, they travel Back to The Future to today. The story of what happens is chronicled in the excellent film: Back To The Future II.
The film itself, as well as the other two in it’s series did an excellent job at going over time travel. In our alternate reality world where America is communist there’s only one change to the film. Instead of Libyans providing the plutonium, it’s radical ERA members. Otherwise, the film is more or less the same, it’s one of the staples of the space time continuum.