During the flashback showing Logan Delos' first contact with Ford and Arnold's first hosts, a piano cover of "Runaway" by Kanye West plays in the background. Other classic piano compositions play in the episode, like Sergei Rachmaninoff's "Morceaux de fantaisie, Op. 3: II. Prelude in C-Sharp Minor" at the beginning of the episode, in cold open, and Frédéric Chopin's "Piano Sonata No. 2 in B-Flat Minor, Op. 35: III. Marche funebre, Lento," played by Dolores at James Delos's retirement party. After he asks her to play "anything but fucking Chopin", she switches to the Gershwin piece "The Man I Love", which had already been performed earlier in the episode by host Clementine at the demonstration for Logan. "Reunion" was watched by 1.85 million viewers on its initial viewing, and received a 0.7 18–49 rating. With three days of DVR viewing, the episode gained an additional four tenths in the 18–49 demographic to achieve a 1.1 18–49 rating. Overall the episode had an audience of 2.98 viewers, and a 1.2 18–49 rating with seven day DVR viewing. "Reunion" received critical acclaim. The episode has a 95% score on Rotten Tomatoes as of 2019, with an average rating of 8.53 out of 10, based on 38 reviews. The site's consensus reads "'Reunion' moves Westworld forward with a fascinating look back, shedding light on the park's mysterious origins to answer some important questions and raises a few new ones." David Crow of Den of Geek US rated the episode 4 out of 5 stars. Ron Hogan of Den of Geek UK said the episode had "a beautifully wrought script" and that "battle lines continue to be drawn in "Westworld" season 2". IGN gave the episode a score of 8.8 out of 10. "Vulture" gave the episode 4 stars out of 5, stating the recap of the episode was "A Place Hidden from God". Caroline Framke and Emily VanDerWerff of "Vox" said "Reunion" had "finally answered some big questions", but questioned why characters "talk in monologues all of the time". Adrienne Gibbs of "Forbes" said the episode was "full of splendor and origin stories".