Uncle Arthur gives Darrin a magic amulet to protect him from harm. He "shoots" him with a gun and you see two burn marks on Darrin's pajamas. They are still there when Arthur makes Darrin climb the ladder. But they are gone after he makes Darrin jump.
When Arthur gave the amulet to Darrin, he shot at him 2 times. Behind Darrin, one can see 2 bullets holes appearing on the green wall. Soon after, these 2 holes are not there. Also, one can notice there is a dresser in that location but, it is moving from scene to scene. Earlier, when Sam is in the room, talking to Darrin, this dresser is far from the room door. After Arthur shoots Darrin, the dresser is closer to the door.
Sam had screwed the finial onto the lamp but when she departs, at the very end, she picks it up from the lamp, without unscrewing it.