Rotten Tomatoes
Movies Tv shows RT App News Showtimes

The Flash – Season 3, Episode 21 Cause and Effect

Play trailer The Flash – Season 3, Episode 21 Cause and Effect Aired May 9, 2017 Drama Action Adventure Fantasy Play Trailer Watchlist
Watchlist Tomatometer Popcornmeter
80% Tomatometer 10 Reviews
Barry goes to extreme measures to stop Savitar; H.R. pushes Tracy Brand to design a trap; Killer Frost returns with an interesting proposal.
Watch on Fandango at Home Stream Now

Where to Watch

The Flash — Season 3, Episode 21

The Flash — Season 3, Episode 21

What to Know

Critics Consensus

"Cause and Effect" skillfully balances ominous foreshadowing with light-hearted romance in an episode rich with needed backstory.

Read Critics Reviews

More Like This

View All
DC's Legends of Tomorrow 89% 56% DC's Legends of Tomorrow Watchlist TRAILER for DC's Legends of Tomorrow Naomi 91% 43% Naomi Watchlist TRAILER for Naomi DC's Stargirl 94% 74% DC's Stargirl Watchlist TRAILER for DC's Stargirl Pushing Daisies 96% 95% Pushing Daisies Watchlist No Ordinary Family 73% 83% No Ordinary Family Watchlist Discover more movies and TV shows. View More

Cast & Crew

View All

Grant Gustin

Barry Allen

Candice Patton

Iris West

Danielle Panabaker

Caitlin Snow

Carlos Valdes

Cisco Ramon

Tom Cavanagh

Dr. Harrison Wells

Jesse L. Martin

Detective Joe West
View All

The Flash — Season 3, Episode 21

View more photos

Critics Reviews

View More
Angelica Jade Bastién New York Magazine/Vulture 08/02/2018
4/5
As much as I love witnessing Barry and Iris fall in love all over again, I also want to understand more about who she is on her own. Go to Full Review Chancellor Agard Entertainment Weekly 07/26/2018
B+
I loved that HR and Tracy kissed in this episode. I found their entire flirty subplot incredibly charming. Go to Full Review Scott Von Doviak AV Club 07/25/2018
B+
It's a very meta episode, and I'm not talking about metahumans. Go to Full Review Noetta Harjo Geek Girl Authority 04/22/2020
For the entire season, we have been dealing with the cause and effect of Flashpoint. I'm kind of ready to move on. Go to Full Review Ja-Quan Greene Black Nerd Problems 08/02/2018
The subtle foreshadowing game was on point. Go to Full Review Jesse Schedeen IGN Movies 08/02/2018
9.3/10
Such a breath of fresh air... It's no coincidence that the best Flash episodes this season have been the ones to fight back against the darkness and focus more on lighthearted comedy. Go to Full Review Read all reviews

Episode Info

Synopsis Barry goes to extreme measures to stop Savitar; H.R. pushes Tracy Brand to design a trap; Killer Frost returns with an interesting proposal.
Director
David McWhirter
Executive Producer
Greg Berlanti, Andrew Kreisberg, David Nutter, Sarah Schechter
Screenwriter
Judalina Neira, Lauren Certo
Network
The CW
Rating
TV-PG (L|V)
Genre
Drama, Action, Adventure, Fantasy
Original Language
English
Release Date
May 9, 2017
More Top TV Picks Netflix