Fruit of the Poisonous Tree - S1-E11
Continuity mistake: When Emma takes out Sidney's card at Henry's playground, in the first shot, her hand is closed around the bottom of the card. In the next shot, she's holding it between her thumb and index finger, with the thumb on top of the card. (00:07:10)
Continuity mistake: Belle is talking to Rumplestiltskin and sitting on his dining room table. The red rose in the vase he gave her keeps moving. It is leaning to the right, to straight up, then to leaning to the right again. Neither of them touch it, so it should not be shifting around.
What Happened to Frederick - S1-E13
Continuity mistake: At Lake Nostos, Charming drops his cloak and scarf by the shore. In the following shots, the garments keep changing position on the ground. (00:20:00)
Continuity mistake: When Mary Margaret and Emma are walking down the street, as Mary Margaret says, "This is the best I can do", she begins to walk past the corner of a building. In the next shot, they begin to walk past it again. (00:05:15)
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: In the scene where Emma is taking pictures of Kathryn's car and Sidney shows up, they open the trunk lid. None of them close it, and the camera is on them the whole time, but when David shows up, the lid is closed. (00:08:00)
Continuity mistake: When Bossy is cutting Dreamy's beard, Dreamy asks "Who was the woman I saw?" and Bossy stops cutting, but a couple of shots later, Dreamy's beard is suddenly much shorter. (00:10:00)
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: In "The Shepherd", Kathryn is showing David their house, and you can see that the street number on the Nolans' house is 244. In this episode, when Emma is looking at Kathryn's phone records in the evening, the phone records list her address as number 4. (00:38:25)
Continuity mistake: Leroy is walking by and Astrid she accidentally dumps glitter on his head. She wipes his face off; he has glitter on his moustache. It disappears. The camera pans back to him and there is glitter on his moustache again.
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)
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)
Continuity mistake: After Charming gives Rumpelstiltskin his cloak, the cloak keeps changing position on Rumpelstiltskin's table. (00:22:05)
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: 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)
Continuity mistake: When Jefferson hands Emma the scissors, the sharp end is pointing towards Emma. However in the next shot the sharp end is pointing in the opposite direction. (00:24:35)
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 Emma and Jefferson are struggling over the gun, the gun keeps changing position on the floor, without anyone touching it. (00:34:00)
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: 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)
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.