Jarvan's quote "Today is a good day to die" is ultimately believed to come from the one of the Lakotan war chiefs, either Crazy Horse or Sitting Bull. It also could be a reference to the power up cheat code in the game Warcraft II : Tides of Darkness or commonly used by the Klingons in Star Trek fiction. Some argue that this quote may also come from the Corsairs in Starcraft Broodwars.
Jarvan's quote "Ours is but to do and die" is a reference to a line in The Charge of the Light Brigade by Alfred, Lord Tennyson.
Jarvan's quote "For my father, the king" is also spoken by Arthas, a playable character in the game Warcraft III: Reign of Chaos.
In the Polish client, one of Jarvan's quotes is "We won't forsake the land we came from" (org. Nie rzucim ziemi, skąd nasz ród). This phrase comes form Polish poem Rota(The Oath), which was proposed to be Poland's national anthem after World War I.
Moved by Shyvana's plight, Jarvan IV assisted her in slaying the mighty dragon that killed her father. After the battle, Jarvan IV offered Shyvana a place as a noble warrior in the ranks of the Demacian Elite Guard. Out of gratitude and necessity, Shyvana accepted.
In Poppy's backstory, she delivers a helm that she and her father had made. This was said to have been very important, and also was described as having a jewel in the front, similar to Jarvan IV's helm in his classic skin.