"You know what's funny about your dad, Nora... is he hates me. Hates me with a passion. And yet, a version of him is Savitar. A much bigger jerk than I ever was."
Eobard Thawne to Nora West-Allen
"What's Past is Prologue" is the eighth episode of the fifth season of The Flash, and the one-hundredth episode overall. It aired on December 4, 2018.


In the 100th episode, Barry and Team Flash come up with a plan to stop Cicada. However, the plan calls for Barry and Nora to travel back in time to gather some key necessities. However, Barry hesitates, concerned about his daughter seeing certain parts of his life. Meanwhile, Sherloque takes his concerns about Nora to Iris, and Caitlin turns up a key asset in the fight against Cicada.[src]


  • The episode's title is a reference to a famous line from the William Shakespeare play The Tempest.
  • This is the only episode where each main antagonist of the series so far appears.
    • However, DeVoe only appears in archive footage.
  • At the beginning of the episode when Ralph and Sherloque are sitting in a car snapping pictures of Orlin, Ralph asks how may pictures Sherloque's taken. Sherloque says, "I've shot like a hundred". This may be a nod to the fact that this the is the 100th episode of the series.
  • Sherloque and Thawne compliment Nora as a "clever girl". These were the famous last words of Robert Muldoon from Jurassic Park.
  • Thawne mistakenly refers to Nora as "Dawn", a reference to Dawn Allen, Barry and Iris' daughter in the comics in the original timeline. He also claims that "at least [Barry] still [has] one." This may be a reference to Barry and Iris having two children in the comics, the Tornado Twins: Dawn and Don Allen. However, in the context of the show, Eobard is more likely referring to how he killed Nora's namesake and Barry's mother, Nora Allen.
  • When Thawne is trying to figure out who Nora is, he guesses the names of three heroes:
  • It is revealed that Eobard somehow knows of Savitar, as he has already seen the latter's face to make fun of it.
  • At one point, Gideon was about to say that Nora is the fifth recruit of a rebooted Legion before Barry interrupted her. Similarly, in the "The Trap"​​, Gideon was about to say that Barry is the founder of an organization before he interrupted her.
  • Barry tells Nora why Thawne killed his mother in the context as he was told by the Reverse-Flash in "Fast Enough".
  • Ralph plays the Huey Lewis and the News song "Back in Time" as Barry and Nora time travel into the past.
  • The times Barry and Nora traveled to are from the following episodes:
  • When Barry and Nora return to the present, Ralph asks, "Did you even go?" (since they returned to the moment they left). Caitlin asked Barry the same question when he returned to the present after running back in time in "Flash Back"​​​​​.
  • Despite being credited in this episode, LaMonica Garrett only appeared in the opening scene from "Elseworlds, Part 1"​​ that was shown as a teaser at the end of this episode.
    • That scene was also used in the Supergirl​​​​ episode "Bunker Hill"​​​​​, and Arrow​​​​ episode "Unmasked"​​. However, it was most likely made for this episode since it was directed by Tom Cavanagh like the rest of the episode.[1]


  • There are a few inconsistencies to the past seen when Barry and Nora travel back in time:
    • When Iris shot Savitar in "Finish Line"​​​​, he fell lying face-up. In this episode when Barry and Nora travel back to that night, Savitar was lying face-down after Iris shot him.
    • After Zoom kidnaps Caitlin, Cisco runs and calls out to her. In this episode, he is shown looking from behind a closed door, which wasn't closed during the events of "Versus Zoom"​.
    • When Barry and Nora travel back to the events of "Versus Zoom"​, Iris checks on Barry after Zoom steals his speed. However, in the original episode, Iris checked on him before that happened.
    • The hairstyle Eobard Thawne was sporting is completely different to the one he was seen with in "Flash Back".
  • Zoom doesn't appear to recognize that Barry traveled back in time; when alerted to Barry and Nora's presence via their usage of the Speed Force, he didn't ask how Barry had his speed back, which he'd taken from the younger Barry moments earlier. After Barry lost his speed in "Versus Zoom", he didn't regain his powers until three episodes later in "The Runaway Dinosaur".
    • However, it's possible that Zoom had simply deduced that Barry and Nora had come from the future.
  • The timeline is now even more messed up due to the Time Wraith that showed up when Nora and Barry went back to the night of May 23, 2017 (Savitar's defeat) to get a shard of Savitar's armor. The Time Wraith followed them to the day Zoom stole Barry's speed and grabbed Zoom when he went after Barry and Nora. Zoom was taken by the Time Wraith at the wrong time; he was originally captured in "The Race of His Life".
    • However, the Time Wraith could have simply removed Zoom from the Speed Force and returned him to his proper place in time with his memory of the encounter with Nora and future Barry wiped, thus preventing any significant changes to the timeline.
  • The episode's official synopsis states that Sherloque takes his concerns about Nora to Iris. In the episode though, he discusses his findings with Cisco, not Iris.


  1. It's possible that all changes to the past shown when Barry and Nora went back in time are the result of ripples caused by their time traveling.




  1. "DC Daily Ep.63: Exclusive interview with CW ELSEWORLDS crossover star, LaMonica Garrett" - YouTube
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