Nutshell: The alternate-reality premise is okay, but the episode moves at snail's pace and suffers because of some surprisingly weak performances. And the conclusion is painfully routine.
Harry Kim wakes up one morning to find himself in an alternate reality where he lives in San Francisco and everybody treats him as if he had never been on board the Voyager. Unfortunately, the interesting premise is wasted due to execution problems, and the episode has big troubles figuring out its dramatic dynamics.
I like the way this mystery begins, by throwing Harry into a situation where he hasn't got a clue (and neither do we) and must try to wrestle out a solution given very little information. The first act or so seems to be working very well as we sample a day in the life of a misplaced protagonist.
Unfortunately, "Non Sequitur" loses momentum fast, and is sabotaged by some sub-par performances and a rather heavy-handed direction by David Livingston. The underlying problem here seems to be a lack of material that necessitates scene after scene to be drawn out into slow, laborious exercises; almost as if the teleplay timed out early.
In the search for what has happened, Harry begins looking through Voyager's classified files (which to the Harry of this reality should not even be accessible). This makes Starfleet Security suspicious, which begins monitoring his movement. Meanwhile, Harry's search is hampered by the presence of his fiance Libby (Jennifer Gatti), whom he cannot begin to make understand that he does not belong on Earth, but on board the Voyager. In this reality, the Voyager is still apparently lost in space, except that some of the people who were supposed to be on board aren't for some reason or another. Harry Kim is one of them. Another is...Tom Paris.
So Kim looks up Paris, who happens to be in France (no pun intended). Hopefully Paris may have some answers or insights. But Paris has no answers to give him—he's just a pool-shooting drunk who didn't make it onto the Voyager in this reality. (In the show's most entertaining scene, Paris explains to Harry the reason he "missed" the Voyager: because he was arrested by Odo after a bar fight with Quark at DS9 right before the ship left.) This scene has more dramatic depth than anything else in the show, showing what Paris could've been without the chance to prove himself as Voyager's ace pilot. Here, he's just a loser. Brannon Braga's script supplies Paris with some good material and Robert McNeill delivers a fine performance.
Because of Harry's mysterious info-gathering and movement around the planet, Starfleet begins to think he's a Maquis spy. They come to arrest him, and suddenly Harry finds himself on the run. The show supplies a decent foot chase scene, and then Paris comes to the rescue to prove he's not a loser, and the two try to find a way to set things back to normal.
But how can Harry fix the space-time continuum to get back to his reality? Here's where the storyline completely takes the easy, highly contrived road. It turns out that the local restaurant owner, Cosimo (Louis Giambalvo) is an alien assuming human form to guide Harry's integration into this alternate reality. Cosimo explains that there was an accident between Harry's shuttlecraft and one of his alien's "time stream." As a result, things got a little bit shuffled around but, for the most part, back to normal.
I wanted to cover my ears during this preposterous explanation. When they first introduced the Cosimo character, I had a feeling it was going to result in some outrageous "revelation," but I was hoping deep down that I would be wrong. Alas, I was not, and the plot resolution comes down to the most obvious and insipid, simply dropping the solution into Harry's lap. To set things back to normal, all Harry has to do is recreate the accident as "exactly" as possible. For the episode, that means the usual, implausible technical procedures which prove only as convenient or difficult as the story needs them to be. So Paris and Kim break into Starfleet and steal a Runabout so they can re-alter reality.
Alternate reality stories can be fun, because it gives a chance to explore character dynamics that would ordinarily not be possible. But aside from the brief moment where we see Paris' apathetic lifestyle, there is nothing at all dynamic about the characters in "Non Sequitur." Garrett Wang's performance is sometimes passable, but Jennifer Gatti's portrayal of Libby is so sluggish that it manages to sabotage almost every scene between Harry and Libby. Based on the chemistry between these two characters, it's no wonder that Harry decided he couldn't stay in this reality!