Early in the film, there is talk about donating Elizabeth's organs. If they really intended to do that, she wouldn't have been taken off of the ventilator, causing permanent hypoxic damage to the organs. Instead, she would've been declared brain dead, the organs would've been harvested soon after, then she would have been disconnected from the vent.
In the last scene where Matt, Alexandra and Scottie are sitting on the couch together- Matt says to Scottie "Strawberry, Mocha Chip," but Scottie is actually eating vanilla (or similar to vanilla's color) ice cream.
As Matt is running down the beach when Brian approaches, the beach is "natural". As Brian passes, the beach over Matt's shoulder has been raked, specifically where Brian is running. As Matt turns and chases Brian, the beach is "natural" again.
When Matt meets Brian for the first time in the beach house, Brian is wearing a blue and white checkered shirt. While talking alone in the kitchen, the back collar of the shirt alternates between down and folded up between shots.
After Julie has left the hospital room and Matt is looking at Elizabeth, her right hand is away from her left. In the next shot, from behind Elizabeth, her right hand is turned closer to her left, even though she can't move her hands.
The door next to Elizabeth's room is almost closed after Alex comes out. When Alex goes back into the room with Scottie, the door is more open and a blue dispenser bottle is next to a small white hand towel.
When Matt and Alexandra talk with Robert Forster's character on his back porch, he changes seats at the table between shots. Between cuts he moves from the chair nearest the lake, to the chair closest to the sun room, back to the chair nearest the lake.
When Matt approaches Julie as she stands on the beach watching her kids, her hands are on her hips, with her thumbs facing forward. After Matt comments the kids are a handful, her hands are still on her hips but her thumbs are facing backward.
After Matt learns of his wife's infidelity, he runs over to his neighbors' house to get more information. He wears flip-flops on his feet while running. When he walks back to his house after seeing the neighbors, he is wearing moccasins.