- Actor-Shared Background: Lena's birth mother is revealed to have been of Irish descent. The actress playing Lena, Katie McGrath, is Irish.
- Dawson Casting: Jon Cryer is only a few years younger than the actress who plays his mother.
- With Lex dying from cancer, his appearance as older than his actual age fits.
- Mythology Gag: The music that plays during Lex's escape is Mozart's "Eine Kleine Nachtmusick", which is also whistled by Lex in Superman IV: The Quest for Peace, right before his escape from the prison quarry.
Trivia / Supergirl (2015) S4E15 "O Brother, Where Art Thou?"