At 49:50, while Donnie is monitoring the surveillance camera feeds, his headphones jump positions. They go from being off, to on with just the left ear covered, to fully on.
At 41 minutes the ballerina figurine shifts the direction it's pointing in between shots.
At 00:18:30, when Detective Mark Lewis and Dr Elizabeth Klein enter the barn to speak with John, Elizabeth places down two lidded takeaway cups in a tray, that she has been carrying, down on a bench beside her.
After speaking briefly with John, Elizabeth asks for a blanket for him, from the police officer present, and the two takeaway cups are still together in the tray. A moment later the camera angle changes and as she stands up to place the blanket around John one of the two cups is now out of the tray and beside John on the bench.
The convenience store employee screams, "Holy shit, call the cops!" over his cellphone, but his lips don't move.