I cannot refute that this is possible, I can however say that based on how you currently describe it, it seems exceedingly unlikely. Whereas, there is no possibility that the laws of gravitation are incorrect in the way that they describe the behavior they pertain to.
Of course to you there may be no possibility that the laws of gravitation are not correct, because you have been schooled to believe that and read books that describe it all...not to mention being around your peers discussing it and fine tuning each otehrs thoughts on it.
Why should you believe anything to the contrary, right? I agree. I mean, surely some random dipshit like myself coming along and simply putting stuff down like I do, is for one...not scientific in the way it's put forward and two, who in the hell am I?
Having said that. If a film maker or an author wants to make a film or pen a book about time travel to incorporate various aspects, he/she must do their full homework.
The film or book can have the story written, then looked over by a select amount of people to see if any flaws can be picked up in the story. If it is deemed feasible, it can go out for showing.
We read the book or watch the film and think, "wow" what a great story, it's just how it would be if time travel happened.
In all seriousness, it's no different to the on going story of what we are reading today, it's just that it's a good story and few people attempt to pick out potential flaws because the way it's written leaves no real scope to argue it and produce evidence to back that up anymore than there is full evidence for the writers to physically back up their own story.