Tomorrow Is Yesterday is one of those Star Trek episodes that just leaves me wishing there was some way I could unsee what I've just seen.
It's that bad.
Not only is the episode resolved using technobabble, a pseudo-scientific deus ex machina (I think you all know how I feel about dei ex machina) if you will, it's technobabble that contradicts what we already know about the technology being used (the transporter). To add insult to injury, the actions of the Enterprise crew, especially those of Captain Kirk, are completely inexplicable to the point of being moronic. If this episode didn't involve time travel, that staple of science fiction that induces headaches in writers and readers (or viewers) alike, it wouldn't be so bad. However, Kirk's actions in this episode lead one to suspect that the bulk of the seventeen separate temporal violations for which he's supposedly responsible (according to Lucsly and Dulmur, the humorless agents from Temporal Investigations, in the Deep Space Nine episode Trials and Tribble-ations) occurred in this episode.
If you haven't seen Tomorrow Is Yesterday before, this is what happens:
The Enterprise is thrown back in time to 1969 as a result of a chance encounter with a “black-star” and ends up swanning about in Earth's atmosphere (the Enterprise was headed in the direction of Earth at the time of the accident). The Enterprise is detected by the US Air Force and a fighter is scrambled and intercepts the Enterprise. Kirk responds to this threat by ordering a tractor beam to be locked onto the fighter. Not surprisingly, the flimsy 20th century aircraft breaks up as a result of being manhandled by the tractor beam.
This was probably Kirk's first mistake.
One could argue that it wasn't really a mistake since Spock brought up the possibility that the fighter could have been armed with nuclear missiles so Kirk was merely trying to protect his ship and crew. Fair enough. However, Kirk then compounds this possible error by ordering the pilot to be beamed aboard the Enterprise.
Why do this when the pilot could have ejected from his stricken aircraft? Once the pilot, Captain John Christopher, is brought on board, Kirk proceeds to gives him the grand tour of the Enterprise while admitting he's from the future and providing him with information about said future. What possessed Kirk to do this? As soon as the pilot was brought aboard, he should have been stunned (or at least Vulcan nerve-pinched) and then transported back to the Earth's surface, possibly doused with Romulan ale for good measure to make anyone doubt any stories he might have had about his encounter with “little green men”. Later in the episode, Kirk and Sulu infiltrate Christopher's airbase to recover photographs of the Enterprise that he took before his fighter broke apart, photographs which were recovered from the wreckage of his fighter which leads one to ask the following questions:
First of all, if Christopher's fighter broke apart as a result of the Enterprise's tractor beam, couldn't that same tractor beam have brought the fighter's wreckage on board where the film from its camera could have been removed, sabotaged or swapped out before dumping the crippled aircraft back to Earth?
And if Kirk and Sulu had to infiltrate the airbase, couldn't they have been kitted out with more appropriate clothing like, say, USAF uniforms instead of beaming down in their freaking Starfleet uniforms?
I could go on but my head is already beginning to hurt so I'll have to cut this short. I will say that the means by which the crew of the Enterprise basically “erases” their mistakes is simply bonkers: They go back in time and transport Christopher and a hapless USAF airman, who also got accidentally kidnapped during the episode, on top of their former selves!
Given what we know about transporter technology, the likely result of such a maneuver should have been something like this.
Instead, Christopher and the airman merge with their former selves and lose all recollection of what had happened to them.
And easy peasy, all the mistakes made by Kirk and his crew are erased.
Less said (or thought) the better.