When James is eating at home alone, he flips his spoon into his water glass. In some shots it's leaning against the right side of the glass, and in other shots it's against the left side.
When Jim returns home after losing his parents, his nanny slaps him. The actors had practiced a fake slap and fake reaction, but Spielberg and the actress playing the nanny conspired to make the slap real when the cameras were rolling, so Christian Bale's reaction would be genuine. Therefore, Bale is really being slapped, and his shocked reaction is no act.