The aerial view of Corto Maltese towards the end is actually a view of the Rock of Monte Carlo. The grey stone building above the sea is Monaco's Oceanographic Museum.
AmerTek, first mentioned in this episode is the former workplace of DC character John Henry Irons who would later become Steel.
The letter from Thea to Roy reads: "Roy, I'm sorry. I made a mistake. Thought I could still be with you. Thought I could still be Thea Queen ... But Thea Queen was trusting. And I don't trust you. Or anyone. Not anymore. Thea Queen was also weak. And no matter what it takes, I will be strong. Don't try to find me. You won't. Even I don't know where I'm going. I only know one thing ... I am never coming back. Goodbye, Thea"
When Felicity answers her phone, she tells the caller she can't come in because there is "a death in the family." This is a reference to a highly popular Batman comic title.
Felicity refers to Sara as an Amazon, an invincible woman warrior or goddess. Diana Prince, aka Wonder Woman, from the DC Universe, is an Amazon and demigoddess.