Jay teases Bart and Nora that he has a meeting with President Luthor, an homage to Lex being elected president in the comics. Earth-Prime's version of Lex Luthor, played by Jon Cryer, was actually banished to the Phantom Zone in the series finale of Supergirl (2015).
There are various nods to DC's Legends of Tomorrow (2016) by showing the Atom and Firestorm suits, mentioning "fixed points," and Booster Gold's newspaper appearance.
Eddie and Iris's interaction fills in details from Iris's story from Pilot (2014) of how she started dating Eddie.
This takes place almost entirely before Armageddon, seeing as in Armageddon, Part 1 (2021) the Royal Flush Gang's casino heist on January 1st is mentioned, and in this episode it's shown that the Royal Flush Gang formed and robbed the casino on December 31, 2013 due to Nora and Bart's presence in the past.
This marks Rick Cosnett's first time portraying Eddie Thawne or his likeness since Into the Speed Force (2017), which aired almost exactly five years previously (on March 14, 2017).