Continuity mistake: When Grace and Ms. Mills are sitting in the living room you can see a clock on the right, but in the next shot it's disappeared.
Continuity mistake: Before both kids go out by the window, Anne is painting, and the paint shows different patterns in each shot. (01:21:25)
Factual error: When Grace goes into the children's bedroom to wake them up to introduce them to the new nanny and maid, she takes the only lamp they had with her into the bedroom but light is still reflecting off the nanny and maid as if a lamp was still there. (00:08:20)
Factual error: As Anne is standing in a room at the beginning of her punishment, the camera pans sideways from her past a piece of furniture with a small statue on the top of it. From behind the statue comes a light whose color and quality could only be electric in origin. It is a greenish fan of light, like one of the old "TV back-lights". (00:27:45)
Continuity mistake: When the father comes home, the scars on his face are very small - in the bed scene they are a lot bigger. (00:55:45 - 01:04:20)
Continuity mistake: Anna's eyes keep changing throughout the whole movie. One scene they're brown, another they're blue, then they go to brown again.
Other mistake: When Ann makes fun of the mute at the dinner table, the mute wears a plum-burgundy dress. Later on when Grace runs down to the gate and hears Ann crying, she's wearing the exact same dress. Seems unlikely the woman of the house would wear the same clothes as the scullery girl.
Continuity mistake: When Grace is explaining the children's photosensitivity to Mrs. Mills, she lights an oil lamp, yet a large shadow of the picture frame then appears directly above the flame. This would seem to be cast by a handheld lamp somewhere off to camera right.
Other mistake: When Anne and Nicholas are trying to sleep and Victor keeps opening the curtains, Anne gets up to close them, and then you hear Victor run across the room and open them again. However the silhouette that is supposed to be Victor opening the curtains appears to be Anne's. You can plainly see her longer hair, and when we see Victor in the end, he has a very short haircut.
Continuity mistake: When Anne and Nicolas are at the dining room table having soup, you can see that Anne's spoon is next to the bowl and not in the soup itself while she is reading and not eating. A few seconds later she still has the book in her hands, but now the spoon is in the soup. (00:24:05)
Continuity mistake: When Grace opens the kitchen and all three head in, Mr Tuttles is on his side. When it cuts to him coming through the door his right arm is up and on the door frame.