Continuity mistake: When Frank meets Sarah in the flesh for the first time, she throws numerous items at him. When she picks up a candle holder and throws the candles at him, a third of one of the candles remains stuck to the holder. After Frank tells Sarah, that people are trying to kill them, Sarah replies "Why would anyone want to kill me?" In this shot, the third of the candle is currently on the right hand side of the candle holder. Then when Sarah says "Why?" after Frank says they've been listening to their conversations, the third of the candle is now on the left side of the candle holder.
Picture added by Casual Person