When we're talking about iconic movies that defined a whole franchise, we have to talk about Star Trek: The Wrath of Khan. The second movie to feature the cast from Star Trek: The Original Series, this film redeemed a series that got off to a rocky start. It's got ample fanservice for fans of the show to connect with while providing enough backstory to welcome new viewers.
The famous scenes of Spock's death and the infamous scream of Kirk into the communication link are moments that will last forever, and thanks to the internet will provide endless fodder for a million more memes. However, as with all complex stories with a long history, there are several storylines related to Wrath of Khan that were never resolved. Here are ten of them, and luckily they don't make much of a difference in a stellar film.
10 Lieutenant Marla MacGuyvers
In the Star Trek: The Original Series, "Space Seed" the historian that joins the away team to the USS Botany Bay grows rather fond of Khan despite his aggressive nature. There's even some hint of a love triangle here. Kirk seems to be trying too hard to forget her name and patronizes her constantly about her position and her interest in the crew of the SS Botany Bay.
In fact, Kirk seems really preoccupied with her attraction to Khan but we never really find out what's going on there. At the end of the episode, she joins Khan on the doomed planet, but we never find out what happens to her. Khan makes a reference to "my beloved wife" in Wrath of Khan but never says her name so we can't be sure.
9 Carol Marcus
Carol is a big part of the plot and storyline in Wrath of Khan. She built and designed the Genesis project, which is no mean feat. In the next film, The Search for Spock, she disappears entirely. Not just from the screen, but entirely. The way David talks about building Genesis, it's almost as if Carol had nothing to do with it. She must have known he used unstable protomatter to fill in some pesky gaps.
How could she not know that? And what was her opinion of it? She seemed pretty ethical as a scientist, and she was stubborn and determined enough to hide the original experiment underground on an abandoned planet, so that's not likely given her character. We also never find out how or when she found out about David's murder. Considering how important she was it's disappointing not to know her fate.
8 The SS Botany Bay
When Chekov sees the name "Botany Bay" while he's exploring what's left of Ceti Alpha V, he finally puts two and two together. However, he finds the name on cargo carriers, not the actual ship. Chekov's companion, Captain Terell, asks what happened to the ship that the carriers came from, but the question just hangs in the air and is never answered.
Why were only the containers left? Was that a convenient way of taking away their communication devices and seeing to it they were stranded? It's hinted at that the SS Botany Bay crashed, but there was no indication that there was any crash in the "Space Seed," and why would they have crashed? And if they had, wouldn't the Enterprise have noticed?
7 Ceti Alpha VI
According to the plot of Wrath of Khan, the orbit of the planets changed only a few months after Khan and his crew were left there because Ceti Alpha VI, a neighboring planet, exploded. Just exploded, deal with it. How would that even happen? It could have been a meteorite, a cataclysmic geological event or a weapon being used by a malevolent alien race, but we never find out.
And how could the USS Enterprise, with all of its modern technology and brilliant scientific minds, not have been able to predict this cataclysmic event in "Space Seed?" To make this even more confusing, when Chekov returns to the system, he gets the planets mixed up and thinks they're on Ceti Alpha VI, the planet that blew up as if he wasn't on the Enterprise when Khan was there.
Considering who Khan and his crew are, why didn't Kirk tell anyone that they had been found and where they were? There were records of Khan being sent into exile in space, so why was that information not updated, especially in light of the chaos Khan caused on the USS Enterprise? If Khan and his crew are so brilliant, how come they never figured out a way to contact passing ships from Ceti Alpha V?
This leads back to the other dropped storyline of what happened to the SS Botany Bay. In "Space Seed," Captain Kirk enters the incident into his log, so how come Starfleet didn't know they were there? Or maybe they did and deliberately left them, which seems against Starfleet protocols. Then again, the Federation has done some nefarious things. If we were Khan, we would think Kirk marooned me on a doomed planet on purpose, too.
5 Khan's Children
There is a son in this scenario. Well, sort of. He's really quiet, has virtually no lines and isn't even named. Is this really Khan's son, or a younger crew member that he took under his wing? Since his mother is left out of the picture, and we don't know exactly when she died so we never find out for sure. His age is hard to pin down and that's never clarified either.
Apparently, it's only been 15 years since Kirk left Khan on Ceti Alpha V and the young man in question looks to be older than that. Khan has aged considerably but is surrounded by young crew members. Who are they? He didn't have any children with him in the "Space Seed" episode, and the boy dies on the doomed USS Reliant. We never find out any more about him or his siblings, including if they ever even existed.
4 The Genesis Cave
"Can I cook, or what?" Carol Marcus
We get some hint of the power of Genesis to destroy at the end of Wrath of Khan and it's an essential part of the plot in The Search for Spock. We get a hint that protomatter might be responsible, whatever the heck that is, but wouldn't that also have been present in the experimental Genesis cave that Carol and David built in the heart of a dead planet?
That seemed to be progressing along just fine, and we never find out what happened to it. Was this experiment different, conducted without the addition of protomatter? The cave was simply forgotten and we never find out if it suffered the same fate as the planet in The Search for Spock.
3 Eel Mind Control
Isn't it convenient that these vicious little eels were the only living thing left on Ceti Alpha V, and that they can be used to control minds? How did they survive and why didn't the USS Reliant find them? We could also ask why a ship would send two of its most important officers, with all the pertinent security codes and Starfleet access, to personally inspect a harsh environment on what seems like a dead planet.
To be fair, that's a problem a lot of Star Trek stories seem to have, but moving on, an explanation of where these things came from and how they survived the planet's change in orbit would have been nice. It's also convenient that they left Chekov's brain totally intact afterward.
2 The Genesis Bomb
How did a benevolent device intended to create life be made into an interstellar bomb just because Khan decides he needs one? And how could Carol Marcus be unaware of this capability? It's never explained as to how this happened. Khan might have modified it, or it might have had an internal flaw.
It's not explained why they can't beam it aboard the USS Enterprise and stop it, David simply says that they can't but doesn't say why. This is hinted at in The Search for Spock when David mentioned protomatter but scientific technobabble can't pick up a dropped storyline.
1 The Journey of the USS Reliant
This is connected to how the USS Enterprise couldn't see the destruction of Ceti Alpha V coming, but it also has several of its own dropped threads. Chekov was part of the crew during the "Space Seed" episode. How can he not remember that Khan is on Ceti Alpha V? How come his Captain doesn't know?
He has access to all the Enterprise records, doesn't he? Or was something classified? If so, why? How come the USS Reliant couldn't detect life on the planet, even those weird little eels? It's too bad this story remained unfinished, as it seems like something significant happened between the USS Enterprise leaving the planet and the USS Reliant returning 15 years later.