Brainy and Nia travel into the past to find a sample of Kara's blood.
Tropes:
- The Ace: After being caught by a teacher, Brainy runs through basically any course in the resident High School and excels in all of them.
- Aerith and Bob: Maxim Tork and Mitch are a very straight example of this. Nia and Brainy also claim to be named "Brandon and Brenda" while trying to pass themselves off as (different) aliens.
- Anger Born of Worry: The reason why Alex is so strict towards Kara. She doesn't want her and everybody they both care about in danger.
- Arson, Murder, and Jaywalking: Before the timeline is changed, Tork's DEO file lists his prior offenses as "Illegal killing of endangered alien species, horrible taste in sequin shirts."
- The Bus Came Back: Cat Grant, Kenny Li and his mom Amy, and Isabel Nal.
- Cannot Spit It Out: Kara cannot bring herself to tell Kenny that she will be going to college out of town soon.
- Chronic Hero Syndrome: Much to Alex's chagrin, Kara (with the assistance of Kenny) has been playing hero for quite a while now. Professor Tork actually exploits this by setting up an out-of-control gasoline truck to draw her out.
- Clark Kenting: Lampshaded when Nia and Brainy wear glasses for their 2009 disguise, which Brainy calls "the ultimate optical illusion".
- Cliffhanger: Brainy and Nia are captured by the hunters.
- The Collector: Professor Naxim Tork and his assistant Mitch, who hunt down rare aliens to capture and put them on display.
- Cosmic Retcon: Thanks to the creation of Earth-Prime...
- Kenny Li is alive. While originally he and Kara only shared an Almost Kiss and their potential relationship was cut short by his death, in the revised timeline they were boyfriend and girlfriend until Kara left Midvale for college, and amateur sleuths together, with Kenny knowing her secret.
- Kara first experienced Kryptonite as a teenager when she stopped a meteor during prom night, when she originally never heard of it until after she became Supergirl.
- Game of Nerds: Brainy is shown to especially excel at baseball.
- Genre Refugee: Naxim Tork and Mitch's overall aesthetic and personality seem somewhat out of place in the world of Supergirl, and would more closely resemble villains seen in Legends of Tomorrow, a more comedy-centered series of the Arrowverse, or the Marvel Guardians of the Galaxy films.
- Intrepid Reporter: Cat Grant, or CJ, as she calls herself by 2009. She wants to uncover the secrets of Midvale being the "luckiest town in the country".
- It's All My Fault: Nia beats herself up for not interpreting the pink cougar in her dream right.
- Lured into a Trap: Naxim Tork and Mitch lure Nia and Brainy into an ambush and capture them.
- MacGyvering: Brainy rigs various contemporary printer parts into a crude 3D printer.
- Missing Reflection: Dreamer's powers are visible to the naked eye, but don't show up on photographs, which confounds Cat Grant because her pictures of the truck are seemingly worthless until she notices Kara's shadow on the road.
- Never the Selves Shall Meet: The reason why Brainy forbids Alex or J'onn to come along, citing Back to the Future.
- Oh, Crap!:
- Tork and Mitch, when they realize a Coluan has entered the scene and is about to de-cloak them.
- Brainy, when he realizes that their encounter with the hunters has changed the future.
- The Rival: By 2009, Cat is apparently in a rivalry with Lois Lane, wanting to get a story that will blow her out of the water by all costs and being offended when she tells a barkeeper she's a well-known Daily Planet reporter and he mistakes her for Lois.
- Shout-Out: Nia's method of coping is singing her favorite song, "9 to 5".
- Time-Shifted Actor: As a result of most of it being set 12 years in the past, Kara and Alex in this episode are played by younger actors, reprising their roles from "Midvale". Cat Grant, or CJ as she calls herself in 2009, is also not played by Calista Flockhart, but by Eliza Helm, and Kenny is now played by Peter Sudarso instead of Ivan Mok.
- Time Travel: Nia and Brainy travel to the year 2009.
- What the Hell, Hero?: Alex blows up at Kara for endangering the entire family by recklessly using her powers and not thinking of the consequences.
