Ashley says at the food table (at the dance) that she's going to be over "there" watching and points to her right. She walks to the right and Jeremy and Mary-Kate begin talking. Jeremy is on the side that Ashley pointed to, and when the camera angles to Mary-Kate, Ashley is shown dancing with a boy behind her, and it's the opposite direction of where she was pointing, and she isn't even paying attention enough to be WATCHING them.
When Kevin was playing his sax in the alley, the lamp light was behind him, so why was his shadow behind him, too?
When Carrie walks in the door and hears the saxophone, she goes to the attic to find Kevin there. If Kevin hired Carrie to watch the girls when he wasn't there, then why would he be home when Carrie got there?
In the pilot, it was established that Mrs. Baker and Mr. Fillmore live next door to the Burke's on either side of their house, on the same street. So, how is it when the girls are spying on them using the telescope, Mr. Fillmore now lives ACROSS the street from them?
When Kevin meets Tara at the school, she asks him to go out TOMORROW night. She says: "Today's Wednesday, so tomorrow will be Thursday." Later in the episode, Kevin tells Carrie that he has to cancel TOMORROW'S date with Nancy, because he met Tara YESTERDAY at the girls' school. So, he said this on Thursday, meaning he had the date with Nancy on Friday, then why did he cancel it? He never says he has something else to do on Friday.
When Kevin returns from his date with Tara, he starts yelling at Carrie about it. Nancy was in the kitchen, why didn't she hear anything about it?
When Ashley is baking cookies, Carrie says that Taylor might enjoy them. Ashley asks why she would care about Taylor, and Carrie answers: "Maybe because you've had a crush on him since the first time he walked through the door." But Carrie wasn't there when Ashley met Taylor (Episode 2: "The Tutor").
Mary-Kate and Ashley also used a Halloween costume swap in a film they were in when they were little called "Double, Double, Toil and Trouble" where they starred as twins to free their Great Aunt Sophie from a moonstone so their parents can keep their house...
Eddie must have been really out of it not to notice "Mary-Kate" had shrunk about six inches after the switch. He should have also noticed because Max's hands weren't covered up, and Max, if im not mistaken, is a completely different shade than the twins.
How is that the kids were able to switch costumes so easily when they're obviously different sizes? Max is taller than the girls and Brian is much shorter, so why did it seem to be perfect fits when the outfits should be too small or too big?
When they are at Carrie's party and Carrie's in the Cleopatra costume, the fringe on her wig hat keep changing position from high-up to low-down and so on.
It's surprising that Kevin wasn't more alarmed when Mary-Kate came in and said that Ashley went through the whole bottle of Pepto-Bismol. Having that much at one time could have really hurt her--but instead of freaking out about that, Kevin just went out and got more.
Hallie Todd, who plays Marci, went on to portray the mother in Hilary Duff's breakout Disney Channel series Lizzie McGuire.
Marci doesn't seem to have a good memory. When she met the girls, she already knew that the sick one was Ashley, and the one that opened the door was Mary-Kate, but later, when Kevin asks her who lied to her, she couldn't remember the names.
In one scene, Max asks Kevin who Marci is, and he answers: "She's a woman I've gone out with a few times," but when he said this, he had only gone out with her once.
The Burkes live in Chicago, but in this episode you can see the World Trade Center in New York.
In the living room, Ashley says that she might be able to force down a slice of pizza. When you look into the box, it is empty.
When Kevin is telling Carrie that Rick isn't her type, there's a moment when he moves his lips, but you don't hear him saying anything.
When the twins are going to bed, Kevin tells Mary-Kate to brush her teeth, so she goes. Less than a minute later, she's back.