fourth season of , and the seventy-sixth episode overall. It aired on November 21, 2017.
- The title is a reference to the philosophical proposition "I think, therefore I am", originally known in Latin as "Cogito ergo sum".
- Marlize asks Clifford if he's seen a video of a Husky singing the Madonna song "Like a Virgin".
- Cisco asks Barry if he's seen "Zatoichi the blind swordsman", a franchise of films and a TV series featuring the eponymous character.
- At the press meeting held by Dr. "Wells" (secretly Eobard Thawne) at the turning on of the particle accelerator, he noted that Barry was present, along with Clifford DeVoe and his wife. Thawne was excited at this and even remarked that he was a fan of DeVoe's "work", wishing him "good luck" for the future. Since Thawne was from the future, he likely knew DeVoe would one day become The Thinker, an enemy to the Flash.
- Eobard Thawne's reappearance as Harrison Wells in this episode is a foreshadowing, as he returns in the crossover event with Harrison Wells' face, with his most prominent callback of being "Harrison Wells" in Part 3, which is the next episode.
- Similar to the comics, Clifford DeVoe obtains his high levels of intellect through his developed and created: "the Thinking Cap", and he even names it the same. Also like in the comics, its use has detrimental effects on the rest of his body, though instead of a slow cancer like in the comics, it is a fast-acting paralysis.
- The scene from "" is shown again. However, it continues on at the press conference after Barry and Iris run after the thief.
- In the flashbacks, DeVoe reveals that 2,600 people were affected by the dark matter of the particle accelerator explosion.
- Barry tells Iris that his "Spidey sense is tingling", referencing the Marvel superhero Spider-Man and his powers.
- When Wally returns to Central City, he talks about fighting a giant starfish from outer space. This is a reference to the Justice League villain Starro.
- This is the second episode in which Barry stays in his civilian persona and doesn't appear as the Flash, the first being "".
- This is the last episode of to credit Keiynan Lonsdale as a series regular, in addition to being credited in the main cast bill, as he became as a series regular in (starting in the episode "").
- Ralph Dibny only appears in the second sneak peak, which ended up being a deleted scene from the episode.
- The date of the S.T.A.R. Labs particle accelerator explosion is said to have occurred on January 7, 2014. However, it was previously stated by Felicity Smoak in the fourth episode of the animated series and Cisco Ramon in the Season 3 episode "" that the particle accelerator exploded on December 11, 2013.
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