"By the way, the stuff from the other movies and the original series about traveling back in time by using the sling shot effect, flying around the sun really fast, never did make much sense..."
If you go REALLY fast in real space, you should theoreticlly end up going back in time. The apparent time slows as you speed up and approach the speed of light, so "logiclly" after a point it should start running backwards.
The problem with that is in order to do that, you need to generate MORE than infinite force. Slingshoting around a sun just ain't going to cut it.
That and your apparent time would reverse, not anything else's. The result would likely be a ship trapped in an infinite loop..go forward one second, reverse the next. You can't go anywhere, the time is too small to react..stasis.
Phoenix-D