Ray urges Obama to "Run Barry run" referencing the often-repeated phrase used on The Flash (2014) to encourage speedster Barry Allen to run faster.
The episode title "Guest Starring John Noble" refers to the fact that it was in this episode that John Noble made his first on-camera appearance as himself portraying Denethor, the Steward of Gondor from The Lord of the Rings: The Return of the King (2003). For most of the season, Noble's role has been the voice-over artist for the character Mallus. The reason he was chosen by the Legends was that his voice had an uncanny resemblance to Mallus. Noble has made a number of noteworthy performances in the sci-fi /fantasy genre over the years, such as Dr Walter Bishop in Fringe (2008), as well as Sleepy Hollow (2013), Salvation (2017), The Librarians (2014), and The Blacklist (2013).
The Legends get actor John Noble to imitate the voice of Mallus. Noble has portrayed the actual voice of Mallus all season.
The Legends actually met "Lord of the Rings" author J.R.R. Tolkien in season two's "Fellowship of the Spear (2017)".
Rip Hunter admitted that he implanted false memories into Ava, who happened to be a clone. A similar scenario occurred in Blade Runner (1982), since the clones leave the incubator chambers fully developed as adults, they have not had the chance to become well-adjusted people through socialization and years of maturation. The implanted memories provide a buffer or filter through which the clones process their emotions. Same was the plot of Resident Evil series, where all clones of Alice had false memories implanted. In the Resident Evil series, Alice was also given a false family like Ava was here, but in the Resident Evil, even the family had false memories whereas here, Ava's family is real human with their own unrelated memories.