In Einstein's equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.
Several openings can be found on the Tornado's manifest.
The Gorn Connection - As the Tornado recovers from the attack, the location of a House Lo'rok supply depot is revealed. Who is supplying the renegade house? Who attacked the Tornado? The answers to these questions await at this remote supply depot.