Mistake: At the road stop when the young Eves attempt to poison Mulder and Scully, the cashier tells them that they have to have keys to the restrooms. She hands the enormous key chains, but when Scully goes to unlock the bathroom door, you can clearly see that there's no keyhole.
Principal setting: Greenwich, Connecticut; San Francisco, California.
Mulder says that Digitalis is a South American plant that can be used as a paralytic drug. This is not true. Digitalis (|Foxglove) is native to Europe, Asia and North Africa. In large doses it can be fatal, in small, it is used to regulate heart beat etc. There is no evidence of it being used to paralyse anything.
Teena's nurse at the social services hospital heard Teena scream, but didn't hear the door to Teena's room being kicked in.
Conspiracy Info: Eugenics projects were carried out in the 1950s, at the height of the Cold War, laying the groundwork for the alien clones like the Gregors, Jeremiah Smith, Kurt Crawford, and the multiple Samanthas.
Continuity: When Scully is reading the report from Joel Simmons' death, we can see that is has occurred on the 7th of November, 1993; which means that whole episode takes place at the very beginning of November, but at the same time Scully and Mulder should be at Alaska (see episode "Ice").
Continuity: We see Cindy and Teena at the table talking with Eve 7, drinking out of paper cups. Later on, when Mulder picks up a cup from the table, it's made up of glass.
Continuity: Scully says that Teena was kidnapped around 11 p.m., though in the kidnapping scene it was said to be 12:35.
Audio and Visual Unsynchronized: While looking for the girls at the truck stop, Scully and Mulder pass the school bus (the one about which the waitress mentioned). We can hear voices of children but when you look at the bus, you can see there are no children inside.
Plot Hole: If the young Eves had the strength to put their fathers into the swings carefully and easily, and heightened strength was one of the genetic traits mentioned by Eve 6, how was Mulder able to subdue them easily by grabbing their arms?
Eve 10: Hello, Eve 8.
Eve 9: We've been waiting ...
Eve 8: How did you know I'd come for you ?
Eve 10: We just knew.
Eve 9: We just knew.
Deep Throat: Actually I was just in the neighborhood... Wondered if I ever told you about the Lichfield Experiments.
Mulder: No you haven't.
Deep Throat: Well, it was the most interesting project. Highest level of classification. All records have since been destroyed. And those who knew of it, denied knowledge of its existence. It existed during the height of the cold war. We got wind the Russians were fooling around with Eugenics. Rather primitively, I might add. Trying to crossbreed top scientists, athletes... to come up with the superior soldier. Naturally, we jumped on the band wagon.
Scully: Time of death was estimated at 2:30 p.m. Same day, only three hours earlier than the Simmons murder.
Mulder: That's Pacific standard time. That makes it the exact same moment.
Scully: It appears we have two serial killers working in tandem.
Mulder: No. Serial killers seldom work in pairs. And when they do, they kill together not separately.
Mulder: Are you at all familiar with the phenomena of cattle mutilations? Since 1967, over 34 states have reported unsolved cases of cattle mutilations. Trace evidence is remarkably similar. Incision marks of surgical precision. The area around the mouth and often the sexual organs have been removed. There's a substantial degree of blood loss but not a trace of blood at the scene.
Scully: How could that be?
Mulder: Exsanguination. If you were to stick a needle into the jugular of any living creature, the heart itself would act as a pump.
Scully: Well, there is the random possibility that two people can have an unrelated likeness.
Mulder: And both just happen to see their fathers exsanguinated. I'd like to cut the odds of that in Vegas.
Mulder: No, he remembers this kid. She told him he should use chlorine to eradicate the dinoflagellates in the swimming pool. That sound like someone you know?
Scully: Mulder, you're rushing me out of the room.
Mulder: No I'm not.
Scully: Do you have a girl coming over?
Mulder: What's a girl? I've got a movie I want to watch on TV. Sleep tight. See you in the morning.
Mulder: What are you doing here?
Deep Throat: Thought we might take in a Warriors game
Scully: She was kidnapped from the social services home around 11:00pm last night. Looks like someone was afraid she might remember too much.
Mulder: Someone or something, Scully?
Scully: Connecticut state troopers set up roadblocks within half an hour. Nothing.
Mulder: Maybe they weren't looking in the right direction. (points up at the sky)
Scully: Death by Hypovolemia. 75% blood loss. That's over four litres of blood.
Mulder: Could say the man was running on empty.
Scully: Mulder, why would alien beings travel light years to Earth in order to play doctor on cattle?
Eve 6: Cut off the chains... then we'll talk.
Mulder: They're probably there for a good reason.
Eve 6: No. Bad reason. I paid too much attention to a guard. Bit into his eyeball. I meant it as a sign of affection.
Eve 6: You and you. You have 46 chromosomes. The Adams and the Eves... we have 56. We have extra chromosomes. Number 4, 5, 12, 16, and 22. This replication of chromosomes also produces additional genes. Heightened strength. Heightened intelligence.
Mulder: Heightened psychosis.
Eve 6: Save the best for last.
Mulder: ... And one girl was just abducted.
Mulder: Po-tay-toe, po-tah-toe.
This episode was originally called "Girls from Greenwich".
The original choice to play the young twins were the Olsen Twins, but they couldn't make an appearance due to child labor laws in the United States (the Krievins twins are Canadian).
The band Eve6 got their name from this episode.
Cindy briefly watches the cartoon Eek! the Cat which later went on to depict Mulder and Scully in cartoon form.
The names of the little girls, Cindy and Teena, are also the names of the wives of writers Glen Morgan and James Wong.
Mulder: Their own mini-Jonestown.
Mulder is referring to the town of Jonestown in Guyana that was founded by Jim Jones, the leader of the Peoples Temple Cult, for the protection of his followers against nuclear fallout in case of a nuclear attack on the US. In 1978, the inhabitants committed mass suicide.
Eve 6: I am her, she is me, and we are all together.
This line is a reference to a lyric from the Beatles' song "I am the Walrus".