Revealing mistake: In the scene where Henry is out on the balcony and Sara comes out carrying a bottle of beer, Henry is leaning with his elbows resting on a ledge. It can be seen that there is some kind of pad or cushion that he is leaning on because you can see it give when he moves. But when they sit the beer bottle down on the ledge the sound effects of a bottle touching stone or concrete can be heard. This sound should not be heard if the bottle touches the pad or cushion that is on the ledge.
Continuity mistake: In the scene where Henry is first learning to walk with the walker, he is in front of the table where he had been sitting. They show a shot of his feet, and there is only tile floor stretching behind him. He only took a few steps and the table (with the attached drawers beneath) should still be visible.