This marks Matt Letscher's (Eobard Thawne) first official appearance on The Flash since Flashpoint (2016), though he did have an uncredited role in The Speed of Thought (2021), as well as appearances in DC's Legends of Tomorrow (2016).
The title is similar to that of The Man in the Yellow Suit (2014). At the end when Thawne, portrayed by Tom Cavanagh, reminisces about his past, a memory is shown from The Man in the Yellow Suit (2014), in which he was supercharging his Reverse-Flash suit in the Time Vault while saying "Merry Christmas."
When talking to John, Thawne mentions a "cosmic odyssey." Cosmic Odyssey was a DC comic book mini-series released in 1988.
Ray Palmer mentions fighting off creatures from Morlaidh with his sword, a reference to the Sword of the Atom comic. This off-screen battle is also in partial reference to his experience with an ion infused sword in Camelot/3000 (2017).
This episode contains flashback scenes from past episodes of The Flash, DC's Legends of Tomorrow, Arrow, and Batwoman.