You knew this was in here. Back to the Future asks all sorts of questions about time: is time linear? Can we create an alternate reality by affecting the past? What happens if we disrupt the space-time continuum? If we run into our parents' younger selves, will they think we're hot?
But, of course, the movie doesn't just make us think about time in the time travel sense. It also causes us simply to reflect on how greatly our parents' world contrasts from our own, and on the similarities we might share, masked as they are by vast cultural differences.
Questions About Time
Are there any inconsistencies or anything illogical about the ways in which time is affected in Back to the Future?
How might time travel be dangerous (other than breaking up your own parents)? Was Doc playing with fire here?
What benefits might arise from having the capacity for time travel?
How much had the world really changed between 1955 and 1985? Were all the changes pretty surface-level, or were there some major, fundamental differences?
Chew on This
The most important question Back to the Future asks about time is whether there is a necessary gulf between children and parents.
There is no way time travel could exist, or else our planet would already be overrun by time-travelers.