When Daenerys is on the boat, she is wearing a necklace with two things on the front. A moment later, she suddenly wears the same necklace, only with one thing.
When Meryn Trant says to Bronn that he is no knight, his mouth isn't moving.
When Margaery is speaking to the orphans of the Battle of Blackwater, as her handmaiden begins to hand out toys to the children, an email notification sound from a computer on the set can be heard in the background.
At the dinner scene with Joffrey and his mother, Margaery comments, "They tell me a hundred wagons arrive daily now from the Reach." There is an audio cut where "hundred" was dubbed in; she clearly mouths "thousand".