The painting Galadriel examines in the Númenórean Hall of Lore appears to depict Elrond's brother Elros, the first King of Númenor, with a beard, perhaps as a visual indicator of his choice to live as a Man. In J.R.R. Tolkien's writings, all human males with Elven ancestry, no matter how remote, are beardless. This means that Tolkien even imagined Elendil, Aragorn, Boromir and Faramir as beardless.
Sadoc Burrows's statement that he has heard of beings turning into stars may be a reference to the story of Eärendil, the father of Elros and Elrond.
Tar-Míriel mentions her "grandfather's great-grandfather". This was Ar-Adûnakhôr, the twentieth monarch of Númenor, who began the persecution of Númenóreans who used the Elvish languages.
This episode takes place previous to the forging of the rings of power (approximately year 1500) and introduces Isildur, whom fans might know from lore as someone who held the One Ring of Power and became corrupted. According to J.R.R. Tolkien's lore, Isildur doesn't take power until "year 3341: Sauron is defeated when Isildur cuts the One Ring from Sauron's finger". Meaning that he shouldn't be born for approximately 1800 more years. The storyline chronology change was made with approval from the Tolkien estate.
The eastern Númenórean port of Rómenna seems to be conflated with the capital city, Armenelos, which is about 75 miles inland from Rómenna on J.R.R. Tolkien's map of Númenor. This is likely because Amazon does not have the rights to Tolkien's works which name and describe the two locations.