Time Travel? As in the human going back in time by reloading an old save? Yes, that's existed in all versions of Civilization and will still exist in BE. Technically even the "Iron Man" advanced setting of SMAC had it, but it made it a bit more painful since it would exit the game upon saving.
Or future shock as in somebody's army is several centuries more modern (historically speaking) than their opponent? That's always existed as well. If the human doesn't focus enough on science and the difficulty level is high enough he could experience future shock, but it's more commonly an AI occurrence.
Edit: It also occurs to me that SMAC had a tech called "Temporal Mechanics", and if I recall correctly it added the most powerful "armor" in the game. (Stasis Field or something similar) We don't know if a similar tech exists or not in BE but BE units are along Civ V lines, it's just that a BE melee strength of 3 may be equivalent to a Civ V strength of 300 if they met in combat. We may need to wait for the entire unit list to be reveled to know if one or more units try to use time as a weapon.
This "armor" worked by generating stasis fields around the attacker. (From the perspective of the outside world they are frozen in time, from their own perspective the whole universe will fly by.) It would be logical for some late game BE units to be described as working this way as there's no reason this couldn't be used for attacking as well.
The "weapon" that was is contemporary was a Singularly Inducer, it would create a mini black hole in the middle of the defenders. This size of black holes actually decays instantly so it's not quite sure which of the many harmful effects of having a black hole inside you is actually what kills you. This would also be logical for some late game BE units to be described as working this way, it might make more sense for this to be on a ranged unit than a melee unit.