Continuity mistake: In the beginning of the movie when Mitch catches the yellow bird under his hat take a good look at the injury (subungual hematoma) he has under his left thumb nail. It takes weeks for these to go away, but Mitch's is gone when we see his left thumb again as he holds Melanie in the kitchen.
Continuity mistake: As Melanie sooths Kathy she has a towel in her right hand that she drops on the green pillow to the left of the couch. We catch a glimpse of it lying there as Mitch runs to put wood in the fireplace. Melanie never touches the towel again but the next time we see it it's in the middle of the couch.
Audio problem: When Mitch turns on Melanie's car radio he turns the tuner knob and stops on the station that he eventually tunes in, goes a little bit forward and then back again to the same spot. The over-dub is not correct as we would have heard the announcer speaking the first time he landed on the station.