‘The Flash S03E21: Cause and Effect’ Review

The Flash is nearing the end of the season with two episodes left after this week’s “Cause and Effect.” While we don’t get a break from Savitar in this episode, they bring a much lighter tone than they have in practically any other episode this season. Cisco has the brilliant idea to keep Barry from making memories, but instead him and Julian completely wipe his memories.

Last week, we saw the reveal that Savitar is a time remnant of Barry. As someone who wasn’t thrilled with the reveal, this episode made it a tad more interesting. Barry losing his memories made Savitar lose his, too. This gave Killer Frost some more screen time as she goes to the lab to work on fixing it with Cisco and Julian. For a brief moment, as Killer Frost is leaving the lab, we see Caitlin come back. It’s one of those moments that gives you hope that they can turn her back and that’s what changes the future for them.

The Flash "Cause and Effect"
Photo Credit: The CW

Barry not remembering anything brings some much needed comedic relief to the show. HR and Cisco have it at times, but it never lightens the mood quite as much as this does. Iris points out that Barry isn’t carrying the weight of the world on his shoulders, and it’s true. We see the Barry Allen who is giddy about having powers, similar to how he was in season one. This episode provided us with a nice little break from the doom and gloom, but Barry regains his memories, as does Savitar by the end.

HR and Tracy have some nice moments in this episode, too. There’s and awkward non-kiss that later leads to a kiss and it’s like they’re two high school kids who don’t know what to do with their feelings. Speaking of feelings, Julian confesses his love for Caitlin as she’s leaving the lab. The Killer Frost in her makes it seem like she doesn’t care, but she does.

The “B” plot in this episode brings us the return of Heat Monger. He’s released because forgetful Barry is testifying in court. It’s his release and a new attack that causes the team to jolt Barry’s memories back into him. It’s nice for Wally to have his powers back, too. Central City needs it’s heroes and they’re back by the end of the episode.

Overall, this episode brought back a feeling similar to season one, but it’s hard to ignore the fact that there are still 2 more Savitar episodes left. Hopefully it’s not a disappointing end, but that remains to be seen.


  • Great acting from Grant Gustin as a forgetful Barry
  • Savitar storyline stills feels dragged out too long
  • HR and Tracy mesh well together, even in the awkward moments

Favorite Lines

  • “Where the hell am I? Is this a dentist office?” – Barry
  • “Looks like you remembered how to save the day.” – Wally“Like riding a bike.” – Barry

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