In one scene Clark (Tom Welling, who is also the director of this episode) says that his location is on "the corner of Marshall and Beeman". The names refer to two directors that are known for directing a handful of important episodes in Smallville: James Marshall and Greg Beeman.
In one scene Chloe refers to surviving a romance with Dr. Jekyll and Mr. Hyde, talking about Sam Witwer's character. Sam Witwer has gone on to play Mr. Hyde in the show "Once Upon a Time."
When Clark finds Parasite after Eva dies of the implanted GPS, he is using a PlayStationPortable (PSP) as the device to track Plastique.
The kryptonite ring is based on one worn by Lex Luthor in the comics when he was first revised by John Byrne as a ruthless, multi-millionaire businessman. Lex wore the ring at all times to make sure Superman kept his distance. Eventually the radiation from the ring infected Lex's hand to the point where his hand had to amputated. Afterwards, the ring passed through several hands before it was found by Superman and Batman. Superman entrusted the ring to Batman and it's that ring which has the kryptonite in Batman's utility belt. In the show, Oliver Queen as the show's Batman surrogate, takes the ring from Lex after killing him.
Eva Greer shares the same last name with Tina Greer, who also was able to shapeshift. Tina Greer first appeared in Season One's "X-Ray" and died in Season Two's "Visage".