Some series do it well. Doctor Who has time travel as a central plot element and tries to keep some amount of reason, consistency, and causality. Take the 10th Doctor episode “Father’s Day”. They cross their own time line and there is a cause-effect relationship to deal with.

ST:TNG had several episodes that used (and abused) time travel, but there was never any consequences. DS9 even had the crew go back in time and Cisco had to impersonate a major historical figure. At the end of the episode the “time corps” come to debrief him and he just smiles and says that if there were any problems, he would know… and they accepted that without sanction or repercussion.

Ah… it could always be worse. Remember “Dallas”? At least we don’t have entire seasons being retconed as a dream.

My early scifi life was heavy on Doctor Who, so to me time travel is as normal as inertial dampeners or faster than light travel. And even in Doctor Who when it was used to reset the end of the world, it wasn’t a complete reset. There was still character development that occurred and lasted past the reset point.

I think to make time travel a feature in a story (unless done very carefully and mindfully) is a mistake. When it’s out in front like that, of course people are going to examine it and pick it apart. Might as well make the inertial dampeners a major plot point.

Of course, my friends will tell me to “never let the facts get in the way of a good story”, but sometimes the facts pull you out of the experience. If a non-scientific, non-geeky person can ask “wait, how does that work?”, how can a geek let it pass? That’s why a high number of time-travel stories miss their mark. After all, we are geeks. While some of us are more deeply engeeked than others, when we see something that just isn’t right, it will chew at us. We tend to think things through, especially logical puzzles. Time-travel is one of those puzzles. We love the ride, but we hate lack of thought put into the mechanics. It’s kind of like Microsoft.

On the whole, I enjoy a well-told time-travel tale, as long as I don’t try to think too much about it.

Star Trek: Voyager was the most egregious offender, with the episode “Year of Hell” a prime example. In this one, nearly all the crew dies, Tuvok is blinded, Voyager herself is half-destroyed… but Janeway rams the Krenim timeship, and everything is magically restored, like it never happened.

I could name a half-dozen more. You want me to? I can…

When done properly, it can be a marvellous storytelling device. To revisit Star Trek, “City On The Edge Of Forever” is an excellent example. Why? Because the time travel device sets up the conflict – in order to save his timelime, Kirk must allow the woman he loves to die. It’s a powerful, dramatic story (let’s set aside the good captain’s reputation as an interstellar gigolo for the time being). There’s no bad guy to overcome, no big heroic action to take. There are no huge world-shaking changes to the characters that need to be erased. In fact, Kirk has to live with his decision- he must allow one woman to die in order to restore an entire universe. Could you make that decision?

Babylon 5 had one- count ‘em, one – example of time travel; but it was absolutely an essential element to the history of that universe, and isn’t a reset button. In fact, it is resolution and setup all in one.

And, lest we forget the good Doctor and his TARDIS….