The Blacksmith Father Ichiro Yamashiro is hinted at as the ancestor of Katana, who recently appeared in the film Suicide Squad. Her real name in the comics is Tatsu Yamashiro. She is a long running DC comics character appearing since 1983. She is the wielder of the Soul Taker Sword and she also appears in season 3 of Arrow played by Rila Fukushima.
This episode marks the fact that Grant Gustin is now the first actor to appear on all four D.C. Comics CW shows: Supergirl, The Flash, Arrow, and DC's Legends of Tomorrow, although he only does voice work in Legends. Later, he would actually physically appear on Legends. He would also be joined by Melissa Benoist and Carlos Valdes, as they would also score acting jobs on all four shows.
Masako father tells Ray that the Shogun ordered his son, Oda, to commit seppuku. Seppuku is a form of taking one's own life that was considered honorable among the feudal Japanese samurai class. Traditionally, the act consisted of stabbing oneself in the abdomen with a short sword to ensure a slow and agonizing death. It is known as Harakari, but Harakiri refers to the action of cutting stomach while seppuku represents the ritual and the traditional procedure of cutting the stomach.
At 30:01Nate says "Do or do not, there is no try.". He then explains that he is quoting Yoda from the Star Wars universe.
Amaya's kimono resembles the robes worn by a Jedi. Maisie Richardson-Sellers had a role in "The Force Awakens"