The best joke in Lower Decks Episode 5 brilliantly mocks the first episode of Star Trek ever aired

In Star Trek: Lower Decks Episode 5, “Cupid’s Errant Arrow,” Ensign Mariner is on a mission. It’s not a mission to explore a strange new world or make peace with an advanced alien culture. Instead, Mariner is all about unmasking her best friend’s new girlfriend as a space monster in disguise. In the newest Lower Decks, this episode-long joke is not only hilarious but it both honors and sends up the very first Star Trek episode that was released into the world, exactly 54 years ago on Sept. 8, 1966. Here’s why this joke is so great and how it uncovers the secret monster trope lurking at the heart of Trek.

Spoilers ahead for Star Trek: Lower Decks Season 1, Episode 5, “Cupid’s Errant Arrow.”

We like to think that from the very start, Star Trek was a super-progressive space adventure that was all about tolerance and acceptance. And while that’s largely true, the very first episode ever aired — “The Man Trap” — was mostly about uncovering a salt-sucking space vampire pretending to be McCoy’s long-lost girlfriend Nancy Crater. Briefly, this same salt vampire also flirted with Uhura in the guise of a hunky dude who spoke fluent Swahili. You could argue that the episode should be called “The Person Trap,” and not “The Man Trap,” but the fact that Bones falls for this and Uhura doesn’t could mean the title actually still works? 

In the new Lower Decks, when Marnier is convinced that Boimler’s new paramour Barb (Gillian Jacobs) is too good to be true, we’re deep into very familiar Trek territory here. Generally speaking, if someone falls in love in the Star Trek universe, there’s a good chance the person they have fallen for is some kind of alien in disguise. “When a Starfleet relationship seems too good to be true, then RED ALERT, it probably is!” Mariner rants, and then lists off all the possible secret identities Barb could really have. “She’s an alien who is going to eat you, or Romulan Spy, or a Salt Succubus or an Android or a Changeling. Or one of those sexy people in rompers who murder you just for going on the grass!” 

Mariner isn't buying it. (Credit: CBS)

In The Original Series episode “What Are Little Girls Made Of?” Nurse Chapel was in love with Dr. Roger Korby, who turned out to be an Android duplicate of himself. In The Animated Series episode “The Survivor,” Lieutenant Anne Nored was in love with Carter Winston, who was really a many-tentacled shapeshifter called a Vendorian. And the sexy people in rompers who murder you just for going on the grass is a reference to the scantily-clad aliens called the Edo, who, in the TNG episode “Justice,” after a lot of flirting and massages, did try to murder Wesley Crusher because he fell in a certain part of grass deemed a “punishment zone.” 

But the reference that sticks out most is  when Marnier says “Salt Succubus.” Kirk, Spock, and Bones never use that term to describe the M-113 creature, but as Trek’s first monster-of-the-week, the Salt Vampire is a classic. Unlike most of Trek’s other shapeshifters, this creature used telepathic projection to make everyone think they were seeing something that they weren’t. That’s why Bones believed his old flame Nancy Crater didn’t look any older than she had been when he’d last seen her years prior. At the end of the episode Spock (infamously) gets into a fistfight with Nancy/the Creature, in which she knocks Spock into a bookcase with like one finger. “Is that Nancy, Doctor?” Spock ominously says, just before Bones is forced to zap the creature.

"Is that Nancy, Doctor?" (Credit: CBS)

Kirk, Spock, and Bones end up feeling pretty bad about taking out the M-113 creature, and the episode ends with Kirk thinking about extinct species like the buffalo (which is apparently extinct in the Trek future). This kind of thing gestures at the kind of progressive politics that Trek would later explore, but in “The Man Trap,” the story mostly falls on the side of a bug-eyed-monster episode. In fact, the most progressive thing about it is probably that scene where Uhura just starts speaking Swahili out of nowhere. Find another show from 1966 in which that happened!

In “Cupid’s Errant Arrow,” Lower Decks has a good time with some of the cheesiness of “The Man Trap.” Just like Spock got into a fight with Nancy Crater, Marnier gets into a drag-down fight with Barb, which only reveals that yes, there is an alien intelligence at work here, but Barb is totally human. Instead, there’s an alien parasite on Boimler, and Barb’s attraction to him is because of that little critter. It’s a hilarious twist and one that allows Lower Decks to do what it does best: Make fun of Star Trek’s past, while also taking an old trope and making it seem new. 

At the end of the day, Mariner was right: Star Trek tradition says that most of these relationships have to end with some kind of alien interference. But, that doesn’t always mean the alien gets zapped at the end. 

Star Trek: Lower Decks airs new episodes on Thursdays on CBS All Access. There are five episodes left in Lower Decks Season 1. "Star Trek Day," the celebration of when "The Man Trap" first aired, and thus, launched Star Trek, is on Sept. 8.