Continuity mistake: As Melanie and Mitch get ready to leave the restaurant for Annie's the hat and coat on the coat rack cast a very dark shadow against the wall. When we saw this spot before there was only of very light shadow against the wall.
Audio problem: After leaving the card by the bird cage Melanie walks on the carpet over to the window to see where Mitch is. She just walked over that spot a minute ago and didn't make a sound, but now they dub in the sound of her walking on a hardwood floor.
Continuity mistake: Mitch takes two pillows from the couch and stuffs them into the openings between the fireplace and the table. Right after he does this each pillow falls but in the later shot the crew has tacked them up again in different spots.
Continuity mistake: When Annie tells Melanie that she still likes Mitch a "hellava lot," watch the shadow of the fancy three-branched lamp to her left. As the phone rings, the shadow of the power cord against the wall in the middle of the screen disappears between shots.
Audio problem: Talking to Melanie Annie gets up and says, "Afraid I'd give Mitch". This sentence is an obvious over-dub as the natural room echo that we hear in her previous and subsequent sentences disappears.
Revealing mistake: As Mitch and Melanie look at the birds perching on the Bodega Bay School they're all fake. The only two that move are to the right of the wire and they're attached so they swivel forward and backward in the wind.
Continuity mistake: As Mitch crouches down near Annie's body he turns to look at Melanie and you can see a large wet stain on the porch. It's there until he sees Cathy in the window, then as he runs to the front door it disappears.
Continuity mistake: When Melanie yells, "Where's Cathy?" Mitch looks up to see her in the window and she is moving the right curtain with her hand as she cries. In the next shot as Mitch runs to the door the curtain is not moving.
Continuity mistake: As Melanie approaches the pet shop cashier she passes two cages on her right with birds in them. The cage with the two yellow birds that she shows to Mitch is not one of them nor is it behind the second cage where it appears later.