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)
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)
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.