Continuity mistake: Maya's necklace disappears between shots when she accuses Sylar of killing her brother.
Continuity mistake: Right before Sylar shoot Maya, you can see she already has a bullet wound on her chest.
Visible crew/equipment: When Mohinder, Sylar, Maya and Molly are at Isaac's old flat (now Mohinder's lab), as Mohinder and Sylar walk down the stairs, you can see the moving camera crane reflected in the glass behind them.
Continuity mistake: Season 2, episode 11, "Powerless":. In Mohinder's kitchen, when Sylar cocks the hammer of the gun he is holding on Mohinder, he is holding the gun with his arm straight and the gun completely level. The angle changes just as Sylar says "Maya, I need you to stay calm", and now his arm is close to his body and bent so the gun is pointing at Mohinder at an upwards angle. There was no time for him to move his arm in between shots. (00:03:30)
Chosen answer: It's not been made 100% clear. It was originally assumed that he actually consumed part of the brain, but this has turned out not to be the case. Sylar has been shown all along to have an instinctive knowledge of how things work and how to fix them - this is his actual original power and the ability that made him an exceptional watchmaker and repairer. It appears that he uses a similar process when acquiring new powers - he exposes the brain of the target, allowing him to examine it and determine how their power functions. He can then apply that knowledge to his own brain, allowing him to replicate the ability in question.
Tailkinker ★