For a movie that jumps back and forth in time, the narrative through line of BTTF is pretty straightforward. Boy has friend. Friend invents time travel. Boy is sent back in time. Boy has to figure out how to leave past. Friend helps boy get back to future.

But while we're living in two totally different time periods, there are no flashbacks or flash-forwards. The storyline is very linear.

Thank goodness, because after watching Zemeckis' other defining work, Forrest Gump, we'd be okay if we never went back in time again. In Gump, life is apparently like a box of flashbacks. Pass the Dramamine, please.