There's a whole lot of fun stuff we could discuss here...
Does freewill exist? If you do go into the future, can you actually do anything about getting back to the 'present'? Or are your actions in the future predetermined?
Why have we not seen time travelers? Is it because when they get back in time, they have no control over what they do - their actions have already been determined?
And can you alter something in the past without altering the future? Can you go back in time, before you were born, and shoot your grandfather? If you can, perhaps it will not change the future because of the distinction between cause and effect. Or perhaps you can't shoot your grandfather because you do not have freewill.
What if it is ever proven that freewill does not exist? What effect would it have on humanity? Would people give up trying to make the world a better place because they cannot control it? And what of the justice system? It would surely fall apart. How can it be right to jail someone who has no control over their actions?
...I'll leave you to it. I'm off to bed!
(As a great man once said, "My brain hurts!")