S.T.A.R. Labs has a hall for mementos of fallen allies, including: Harrison Wells, H.R.'s drumsticks, Harry's glasses, Sherloque's brandy bottle, Nash's bandolier, Snart's goggles, XS's jacket replica, Ronnie and Stein's Quantum splicer, Jesse Wells' jacket, and Oliver Queen's original mask.
Cisco calls TV personality Arielle Atkins "Rachel Maddow 2.0." Maddow has a recurring guest role on Batwoman (2019) as the voice of Gotham talk-radio DJ Vesper Fairchild.
Frost is the second non-speedster to use one of the Velocity serums.
Harrison Wells is shown being revived at some point after Thawne killed him, though it's unknown when. Before this, the original Earth-1 Harrison Wells was never seen--apart of his appearance as a corpse in Who Is Harrison Wells? (2015)--outside of his debut, Tricksters (2015), which aired nearly six years prior to this episode.
Cisco refers to the "Babel Protocols" when he and the rest of Team Flash are trying to detain Barry. This is a reference to the famous Justic League comic book storyline, Tower of Babel, in which it is revealed that Batman keeps secret files on all of his teammates, detailing their weaknesses, in case they ever go rogue.