This is the first episode not to feature the opening monologue.
Cisco links Cicada's ability to control his lightning dagger to Thor being able to control Mjolnir in Marvel comics, making it the third reference to Thor on the show. Thor was previously mentioned in Elongated Journey Into Night (2017) and When Harry Met Harry... (2017).
The transformation Ralph's stylist does to Cisco makes him look like his alternate in Flashpoint.
This episode introduces us to Chris Klein's mysterious villain, Cicada. This is a character who has only made a handful of appearances in DC Comics. He was created by Geoff Johns and Scott Kollins back in 2001 as a Wally West villain.
Cicada was originally supposed to appear as the second cliffhanger scene of We Are the Flash (2018), but it was cut due to time pacing and constraints. The scene was used in the trailer for season 5.