Dr. Hamilton's spasms are similar to Earl Jenkins' in Jitters.
When Pete talks about looking into the girls' locker room with X-Ray vision, it is likely a reference to a similar line from Superman: The Animated Series, The Last Son of Krypton, Part II, which is delivered by Lana Lang instead. Clark's response refers to how he (accidentally) did so in X-Ray.
This is the first out of two episodes featuring kryptonite poisoning. The second, and last, is the episode Fever. Those are the only episodes in which this effect of kryptonite appears or even mentioned.
Duplicity means a deceitfulness in speech or conduct; speaking or acting in two different ways concerning the same matter with the intent to deceive, ie. lying. There are many examples of deceitfulness in the episode: 1. Lana doesn't like her Aunt's new boyfriend, but she hides the truth from her. 2. Lana lies to her Aunt Nell about having a sleepover at Chloe's house. Chloe plays along with the lie, and says they had a "Keanu DVD-athon" 3. Clark lies to Pete about not telling anyone about the ship, and acts surprised when he discovers the ship has been stolen. He actually told his dad about the ship, and knew it had been stolen because he had visited Pete's tool shed with his dad the night before. Pete catches him in both lies. 4. When Pete discovers Clark's powers, he realizes Clark has told many lies over the years. 5. Clark lies to Lex about not knowing the whereabouts of the octagonal key. 6. Lionel lies to Lex about why he left his therapists in Metropolis and was visiting him in Smallville. Lex discovers his lie and confronts him with the truth. Several characters also talk about their attitudes toward lying: 1. Lana tells Clark she's a terrible liar, so she's moved onto avoidance. 2. Lex tells Clark that if a person has deceived him once, he finds it hard to give them a second chance. 3. Lex talks about how his dad has a track record of lying, and it's hard to think he doesn't have an ulterior motive.
Clark uses the following abilities in this episode: super strength, super speed, heat vision, and super leaping.