Continuity mistake: In the scene where Mulan and Aurora are alone in the forest and Mulan is trying to make a fire, she alternates between wearing her long ponytail over one shoulder, and letting it hang down her back. (00:24:45)
An Apple Red as Blood - S1-E21
Continuity mistake: When Regina offers Jefferson a drink, he declines by dropping the white rabbit card in the glass. In the next shot, the card is gone. (00:12:55)
Continuity mistake: When Emma wakes up on Jefferson's couch, her left tank top strap changes position between shots: First, it's at the edge of her shoulder. When she sits up, it's off her shoulder. In the next shot, it's on top of her shoulder, before moving back to the edge of her shoulder in the following shot. A couple of shots later, it's at the top of her shoulder, even though her hands are tied behind her back, and she could not have moved it. (00:10:20)
Continuity mistake: During Emma's sword fight with Hook, when Emma is on the ground, reaching for her sword, Hook sticks his own sword into the sand so that he can drag her away from her weapon. Cuts to a different shot, and his sword is lying on the ground, near his feet. A couple of shots later, the sword is planted in the ground again. (00:27:55)
Continuity mistake: After Hook throws the satchel that holds Aurora's heart to Mulan, the way she holds the satchel keeps changing; most noticeably, in some shots, she's holding it by the straps, in others, the satchel is lying in her hand. (00:28:20)
Continuity mistake: When Emma and August are walking down the streets of Storybrooke in the morning, in the first shot, they are walking past Storybrooke Dental. Cuts to another shot, and they are now walking next to the Clock Tower building. As the shot ends, they are walking past a window covered in newspapers. In the next shot, they walk past the very same window again. Cuts to another shot, and they have suddenly walked past the building as they are crossing the street. (00:01:20)
Red-Handed - S1-E15
Continuity mistake: When David is interviewed at the sheriff's station, after Emma says "And honestly, liars have better material", her left thumb is resting on the edge of the coffee cup in her hand. In the next shot, it's not. (00:01:20)
Continuity mistake: After the door to door candle sales fail, when Leroy is about to deliver the bad news to Astrid, the position of Mary Margaret's coat, which she's holding in her arms, changes between shots. (00:21:00)
Continuity mistake: When Astrid accidentally dumps glitter on Leroy, in the first shot, there's hardly any glitter on him. Cuts to the next shot, and he is covered in glitter. The amount of glitter on his clothes repeatedly changes for the rest of the scene. (00:05:20)
Continuity mistake: The way the baby blanket is wrapped around the infant Emma repeatedly changes between shots. For example, as Charming approaches the magical wardrobe, the blanket has just a tiny opening over the baby's face, and the embroidery with Emma's name on it is showing; in the next shot, the opening is much bigger, and the embroidery can no longer be seen. (00:30:00)
Tallahassee - S2-E6
Continuity mistake: When Hook and Emma find the skeleton of Jack the Giant Killer, in the close-up shot, Jack's sword is in the skeleton's hand. When Emma remarks, "With that toothpick?", the sword is lying beside the hand. When Emma grabs the sword while being chased by the giant, the sword is back in Jack's hand. In addition, the skeleton's arm alternates between being bent and sticking straight out between shots. (00:23:15)
Continuity mistake: When Regina tells Hook about the dark curse, as she says "This new realm", her arm is hanging down by her side. In the next shot, her arm is bent. (00:03:45)
We Are Both - S2-E2
Continuity mistake: When Regina's father, Henry, tells her about Rumplestiltskin, he refers to him as "someone Cora knew before I met her." However, "The Miller's Daughter" establishes that Cora first met Rumplestiltskin while she was locked up in King Xavier's palace, after meeting Prince Henry when she delivered the flour and at the masquerade ball. (00:10:45)
Continuity mistake: When David is having dinner with Regina, as Regina says "How did you like it?" her left hand is lying on the table. In the next shot, her hand is under her chin. (00:20:55)
Continuity mistake: When David is carrying Regina's groceries, there's a plastic bread bag sticking out of one of the grocery bags. The amount of plastic sticking up repeatedly changes between shots. (00:15:45)
Continuity mistake: When Regina is standing by the tree with Daniel, as she says "Have you not seen her magic?" Rocinante, Regina's beloved horse, is standing next to them. In the following wideshot, Rocinante is nowhere to be seen, and there was not enough time to move away from them. (00:08:05)
Continuity mistake: When Regina first kisses Daniel, her head is tilted to the left. In the next shot, her head is tilted to the right. (00:05:05)
Continuity mistake: In the Queen of Heart's maze, when Regina closes the hedge to entrap the pursuers, the spears sticking out from the leaves change position between the wide shot and the close-up. (00:26:10)
Continuity mistake: When the Mad Hatter and The Evil Queen are in the portal of doors, on the left side of the mirror, there's a door with green curtains. The design of the curtains changes between wide shots and the shot where they enter Wonderland. Most notably, in the wide shots, the curtains have brown edges, but when they are standing in front of the mirror, the edges are green. (00:15:55)
Red-Handed - S1-E15
Continuity mistake: In the scene where Ruby reconciles with Granny, in some shots, her necklace is tucked into her clothes. In other shots, it's outside her clothes. (00:36:25)
Answer: He knows who she is because he knows that the fairy tales are true. He was also shown to sneak out to go see Emma or someone else. Sometimes he succeeded, sometimes he didn't. This is how he knew to look for her despite his strict mother.