When Van claims to have killed Clark, Lana calls the police. The sheriff finds him perfectly well after he recovered from the kryptonite bullet, and says "rumours of your death has been greatly exaggerated", a quote of Mark Twain, with the original being "my death".
Lex wonders if he is invulnerable to all diseases. However, Chloe mentions in this episode that Lex has a dramatically increased white blood cell count, a warning sign of many autoimmune diseases. This was also mentioned in Craving when Lex received his annual physical. Also in Craving, Lex is given a clean bill of health, so it's possible that that is just normal for him. In the comics, Lex gets cancer and loses his hand from prolonged exposure to kryptonite by wearing a green kryptonite ring.
Van McNulty's father was the officer killed by Tina Greer in Visage.
This is the first appearance of kryptonite bullets.
Lana's innuendo that Clark is a vigilante similar to Van, and may have killed Tina due to the fact that police found her body impaled in an ally after fighting Clark, is especially ironic because in the previous episode Phoenix, Lana herself performed a fighting maneuver that lead to the death of one of Morgan Edge's henchmen when he was flung backwards and became impaled on a pitchfork.