Continuity mistake: When The Evil Queen crashes Snow White's wedding, the guests alternate between looking at the queen and averting their gaze between shots. (00:02:30)
Continuity mistake: When Sean is visiting Ashley at the hospital, as he says "Yeah, I'm back", baby Alexandra is waving her tiny hands in the air. In the previous and following shots, her hands are down. (00:39:10)
Continuity mistake: After Henry runs up the stairs, he puts his backpack on the bed, with the backside facing upwards. When he takes off his shoe and throws it on the floor, the top of the backpack is facing upwards. When Regina enters his bedroom, the backside is facing up again. (00:38:35)
Continuity mistake: When Ashley is holding baby Alexandra while Emma comes in, her left hand repeatedly changes position between shots; for example, when Emma says "It's pretty", her hand is on one side of the baby's head; in the next shot, it is on the other side. (00:36:25)
The Thing You Love Most - S1-E2
Continuity mistake: Throughout the scene where Emma walks Henry to school, the surroundings change between shots. For example, when Emma asks, "Because I'm the daughter of Snow White and Prince Charming?", they are in front of a clock store. In the next shot of Emma, there's a completely different shop behind her, even though neither of them move. (00:12:35)
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)
Fruit of the Poisonous Tree - S1-E11
Continuity mistake: When Sidney hands Emma a card with his number, the way he's holding it in his hand keeps changing between shots. (00:02:40)
Continuity mistake: After Charming and Snow embrace in King George's castle, Snow's hand is on Charming's chest. In the next shot, it is resting on his shoulder. (00:32:45)
Second Star to the Right - S2-E21
Continuity mistake: When Baelfire eats the bread, what remains of the loaf keeps changing shape and position on the tray between shots, and the two other loaves also move around. When Wendy picks up the tray, all three loaves are untouched. (00:02:20)
Continuity mistake: At Lake Nostos, in the first shot of Emma, Snow and Mulan, there is a giant rock on their left. None of them move, but two shots later, the rock is on their right.
Continuity mistake: At Lake Nostos, when Emma says "You're not going anywhere. This portal's taking us home", in the wideshot, Snow's quiver strap is over her pink cardigan. In the close-up, it is under the cardigan. In addition, Mulan's and Snow's weapons are held at different angles between shots.
Tallahassee - S2-E6
Continuity mistake: When Emma cuts the trip wire in Anton's castle, the surroundings change completely between shots; for example, as she cuts the wire, there is an open chest near her. In the overhead shots, the chest is gone, and Jack's skeleton is missing. (00:33:50)
Continuity mistake: When Snow is dumped by the road by King George's men, the amount of dirt on her clothes keeps changing between shots. (00:14:15)
Continuity mistake: When Mary Margaret is talking to Regina in the school yard, her fringe keeps changing between shots. (00:08:00)
The Return - S1-E19
Continuity mistake: When Emma confronts Sidney, the listening device that she places on the table keeps changing position between shots. (00:15:15)
Character mistake: In the newspaper article that Emma reads, Kathryn Nolan's first name is misspelled "Katherine." (00:19:45)
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)
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)
True North - S1-E9
Continuity mistake: When Hansel and Gretel are outside the gingerbread house, Hansel dips his finger in some icing on the wall, which leaves a mark. Two shots later, more of the icing is missing, even though no one touched it. When Gretel climbs onto the window sill, the icing is fully coated. (00:17:50)
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.