(at around 1h 10 mins) Although story is set in Depression, a Forties era photo of Ingrid Bergman (then unknown to American film-goers) adorns cover of a magazine prominently displayed on a small town newsstand.
(at around 1h 22 mins) After Harry Powell disappears from in front of Ms. Cooper's yard, a barn owl swoops down on a rabbit. We can hear the owl's wings flap even though barn owls make no noise when they fly.
(at around 14 mins) When John is telling Pearl the bedtime story, Harry's shadow appears on the bedroom wall. When John looks outside at Harry at the gate, the angle of the streetlight next to him would not throw the shadow into the house, but on the ground in front of him.
When Harry is stood in front of the Moonlit window and talking to Willa who is lying down on the bed, the 'odd' shaped window frame is projected by the moonlight on the wall behind Harry. When there is a shot of Willa alone on the bed, the shape of the moonlit window obviously frames Willa and not on the wall as before. Although the lighting around her is coffin-shaped and likely to be a framing device.
(at around 23 mins) When Icey Spoon negatively talks about being married to Walt for 40 years at the picnic, his reaction shot shows him set down the piece of chicken. But when Willa calls for John, we see Walt is holding chicken again.
(at around 53 mins) In the basement scene, John pulled down the overhead shelf with the jam or oils pouring over Harry's hairs and shoulders. In the following shot when Harry is trying to grab at John and Pearl, his hairdo remained its normal form without drops of oils or jam on them.
(at around 41 mins) After he drinks direct from the brandy bottle, Mr. Spoon changes the bottle to the left hand to put it in the sideboard. The next shot shows him finishing to set the bottle with his right hand.
(at around 22 mins) When Harry and Willa are talking on the riverside, he has his arms crossed, with his left hand touching his right arm and his right hand holding the hat leaned on his left folded leg. Between shots he appears with his left hand leaning on his leg and his right hand free holding the hat.
(at around 1h 6 mins) When the children are in the boat over night and it drifts onto shore, the oar is positioned one way - after a cutaway to the bow, we see the whole boat again, but now the oar is positioned differently (under John's legs).
When Powell chases the children up the cellar stairs and John slams the door on Powell's hand, the door had been opened toward the cellar. In the next scene, the door shows the closed door with the hinges on the kitchen side, such that the the door would have opened the opposite way, toward the kitchen (not toward the cellar).
(at around 1h 3 mins) When John and Pearl are in the barn at dusk, there is a time-lapse sequence of the crescent moon rising. A crescent moon shortly after sunset is always setting and the lit portion should be tilted toward the point where the sun has recently set.
A man who is sentenced to only thirty days for a misdemeanor would be sent to the county jail, and not the state penitentiary, and thus, would never be sharing a cell with a condemned man on death row.