Continuity mistake: When Dr. Sawyer is giving Kris the exam, during the part where Kris is doing the physical coordination test, we see Kris from Sawyer's point of view, and Sawyer is drumming his fingers. When the shot switches to Kris's, he is fingering his eyebrow. When it switches back, fingers drumming. Finally, when it switches back again, his hands are neatly folded in front of him.
Revealing mistake: Cary Grant shows off his ice skating moves but you can tell it's a stunt double. The double is a bit shorter than Grant. Also in the same sequence, the two other skaters have noticeable doubles as well.
Continuity mistake: To show time has passed, the wooden fence on the beach deteriorates, but the top of the fence, with Anna Muir carved in it, was never anywhere near the water - it was way up inland, far away from the water's edge - but now it is in the water, waves washing over it.
Continuity mistake: Lulu gets out of bed and races to the bathroom to "Brush her teeth." She picks up a tube of toothpaste and a toothbrush, then proceeds to brush her reflection's teeth in the mirror. She does not set down the toothpaste, and when the angle changes as she washes her face, the toothpaste has vanished, not in her hand, not on the sink. (00:01:20)