In the scene where Andrew is explaining how Milo can break into the house, a security monitor shows the ladder against the side of the house. Moments earlier, the same ladder was shown to be on its side on the ground.
When Andrew and Milo are in the guest bedroom and Maggie calls, the phone is not picked up and the illuminated blue display fades once the call ends. In the next shot, the display is illuminated again.
The goof item below may give away important plot points.
When "the detective" reveals himself, he is clearly shown removing, one after the other, his brown contact lenses. At the very beginning of the sequence, there is a prolonged close-up of Jude Law's face where he is clearly wearing only one brown contact. Immediately after this shot he removes the first contact, and only a few seconds later, the other.