Continuity mistake: When the Antereans go into the sea for about the second time I think, Jack stays on the boat and starts playing about with the machine and makes it go off. When it does he drops a load of sweets or nuts out of the bag he was holding, but when the camera cuts away then cuts back there are no nuts or sweets on the floor.
Continuity mistake: Water in the pool becomes instantly still after the old men get out the first time.
Continuity mistake: David goes with his Grandpa when the old man has his eyes tested. David's hairstyle changes from shot to shot. He starts with a center parting and then has a more dishevelled style.