Continuity mistake: In the scene where the Sheriff of Nottingham (his Storybrooke counterpart) tries to apologize to Mr. Gold, they're at the corner of the Rabbit Hole, and in some shots, the clock tower building is seen behind the Sheriff. In other shots, there's a completely different building behind him. In the same scene, Mr. Gold alternates between standing right by the corner, and standing a couple of meters away. (00:35:40)
Continuity mistake: When Mr. Gold and Lacey are on a date at Granny's Diner, when Granny comes with their drinks, she moves her hand towards Gold's glass of ice tea, sitting on the tray. In the next shot, we hear the clinking of ice as Granny picks up the glass, as well as the sound of the glass being put on the table, off-screen, on Gold's left. In the next shot, the glass has mysteriously moved to Gold's right, even though the camera was on him the whole time, and he never moved it. (00:25:00)
Welcome to Storybrooke - S2-E17
Continuity mistake: When Greg Mendell bumps into Henry in the woods, Henry drops his backpack on the ground, the backside facing upwards. When Greg picks it up, the front is facing upwards. (00:28:40)
Welcome to Storybrooke - S2-E17
Continuity mistake: When Henry is in the forest while it's raining, his hair keeps changing, especially his fringe. (00:28:20)
Welcome to Storybrooke - S2-E17
Continuity mistake: When Kurt and Owen are in the diner, in the first shot, Kurt is holding his tankard of beer by gripping the top. In the next shot, he's holding it by the handle, and the vegetables on his plate have changed position. (00:11:55)
Welcome to Storybrooke - S2-E17
Continuity mistake: In Mary Margaret's apartment, when Emma is having breakfast with her family, after she says "He deserves to know", her right arm is resting on the counter, next to the bowl of cereal. In the next shot, both of her arms are resting in her lap. A spoon in the bowl also changes position. (00:10:25)
Welcome to Storybrooke - S2-E17
Continuity mistake: When Emma is having breakfast, the amount of cereal in the bowl in front of her keeps changing. (00:09:55)
Welcome to Storybrooke - S2-E17
Continuity mistake: During breakfast in Mary Margaret's apartment, there are two plates of toast on the bench. The distance between the plates changes between different camera angles. In some shots, they are right next to each other; in others, there is a gap of approximately 30 centimeters between them. (00:09:55)
Continuity mistake: After Mary Margaret opens the birthday present from Johanna, the wrapping, lying around the present, changes position a couple of times. (00:03:55)
Continuity mistake: When David is making breakfast, he turns around, with a frying pan full of pancakes in his hands. In the next shot, he begins to lift up a pancake with a spatula, but when it cuts, he's already holding it out. (00:03:15)
Continuity mistake: At the airport, while Emma is standing in line at the security checkpoint, the way her red scarf is tied around her neck changes a couple of times, and the creases in the scarf repeatedly change between shots. (00:16:00)
In the Name of the Brother - S2-E12
Continuity mistake: When Belle is holding the chipped cup, the cup turns around in her hands when Gold says "It's your talisman." The same thing happens when she tries to give it back to him. (00:34:20)
In the Name of the Brother - S2-E12
Continuity mistake: In the opening scene, the amount of blood on Hook's face and neck from the car accident keeps changing. (00:00:30)
In the Name of the Brother - S2-E12
Continuity mistake: While Hook lies off the side of the road in agony, the position of his arms keeps changing between close-ups and wide shots; this can be seen when the police arrive and Emma finds him. (00:00:30)
Continuity mistake: Aboard The Jolly Roger, Baelfire's shawl, on the bench, changes position between the close-up and the wide-shot when Hook puts it down. The shawl changes position again between when he says "Now, what makes you think you are any different?", and when Belle grabs it. (00:26:10)
Continuity mistake: When Archie's friends are gathered in Mary Margaret's apartment after the funeral, the cutlery in the bowls of salad moves around between shots when Ruby is talking. (00:12:50)
Continuity mistake: When Emma and Henry are having breakfast at Granny's Diner, the spoon in the empty cup next to Henry's plate (on his left) changes position between camera angles. In the same scene, Emma's right hand alternates between resting on the table, and picking at her food. (00:13:45)
Continuity mistake: At Lake Nostos, the pendant on one of Emma's necklaces alternates between being hidden behind her neck (under her jacket) and being visible on her chest. This is seen, for example, when Cora fails at ripping her heart out. (00:27:45)
Continuity mistake: During the battle at Lake Nostos, after Emma lunges at Hook and he flips her to the ground, the amount of dirt on her clothes repeatedly changes. (00:28:00)
Continuity mistake: After Regina places a rose on Cora's body, the position of the green leaves repeatedly changes between shots. (00:22:05)
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.