Jon Cryer played Lex Luthor's nephew Lenny Luthor in Superman IV: The Quest for Peace (1987), According to Cryer himself, he stated that the film's less than sterling reputation was half the reason he accepted the role, alongside his love of the first Superman movie and the comics, as he wanted the opportunity to do the Luthor name justice.
Lex having an inoperable cancer after injecting himself with kryptonite is a reference to the original comics, where he discovered that kryptonite radiation was deadly to humans (if not quite so fast-acting as it is with Kryptonians) after he began wearing a kryptonite ring to keep Superman at bay and later developed cancer.
Jon Cryer was the first and only choice for Lex Luthor.
In the flashback at the beginning, Lex turned the sun red in a bid to depower Superman, a reference to the War of the Superman storyline in 2010, when he briefly turned the sun red to save Earth from an invasion of hostile Kryptonians.
The Luthor family mansion in this episode is the same mansion used in 'Smallville'