When George and Joyce are talking outside the beach house, the shutters on the windows are closed, but when they jump down on the grass, they are open.
When George and Joyce are lying together on the beach, they are closer to the rocks on their right side earlier in the scene than they are later in the scene.
When George is coming out of the water onto the beach, he is coming from a different direction when seen from the water as opposed to from the beach (i.e. he is approaching the beach at the center in the former, while he emerges, from his perspective, on the left side of the beach next to the rocks in the latter).
At the beginning, when the police are examining George's brainless body, it can be seen to be breathing.