Continuity mistake: In the woods after Norma takes the gun away, as she's talking to Norman; her hand changes between shots from resting around his neck to around his ear, with her thumb placed in from of Norman's ear. It changes about 6 times.
Continuity mistake: When Norma is eating at the diner with the college professor, she is eating a burger halfway through. Shortly afterwards the burger is completely new, intact. (00:19:53)
Continuity mistake: When Alex shows up at his house to pack some belongings, he finds his ex-girlfriend Rebecca already there. As Alex and Rebecca talk, the camera pans back and forth while conversing. Alex's jacket is stuck behind his name plate in one shot, then the name plate is completely covered in the next shot. This occurs multiple times. (00:26:20 - 00:27:40)
Continuity mistake: In the V.I.P. room of the strip club, the dancer straddling Norman stands up. In the next shot shown in the mirror, the dancer stands up again.
Refraction - S4-E5
Continuity mistake: When Chick delivers the window he uncovers it. When he leaves it is covered, then uncovered and recovered again.
Continuity mistake: Norma reaches over to touch Chick's walking stick with her right hand, but the next shot shows her using her left hand.
Continuity mistake: Once Chick leaves after unveiling the stained glass window, the protective packing keeps moving position between shots while Norma is speaking with Alex.
Continuity mistake: After Chick leaves, Alex approaches Norma with his arms outstretched. The immediate shot from Alex's rear and his arms are at his side.
Continuity mistake: During Norman's hypnotherapy, he remembers approaching his Dad as he is passed out on the table, and his Dad's right arm is at his side. As Norman comes abreast of his Dad, his Dad's right arm is now on the table.
Continuity mistake: When Alex meets Rebecca in the restaurant and slides her the key, her hands are down. The immediate shot after and her right hand is holding a cup of coffee.
Continuity mistake: Norma's hands change from clasped to unclasped several times as she is speaking with Dylan in the Bates house.
Unfaithful - S4-E8
Continuity mistake: From her left side, Norma is fiddling with her wedding ring while lying in bed with Norman, but her hands are separate in the view from her right side, then playing with her ring as the shot switches back to her left side.
Continuity mistake: When Dylan confronts Norma with the earring of Emma's mother, he is holding it aloft in his right hand. Shots from Dylan's right rear and his hand is at waist level, the next shot from the front and it is held aloft again.
Continuity mistake: When Emma is talking with Caleb in the kitchen, the slice of cake in front of Caleb keeps moving between shots.
The Convergence of the Twain - S5-E2
Continuity mistake: After Norman dismisses Norma's suspicion about him going to "another business meeting" as childish, he heads for the door - the sunlight from outside is flagrant as he opens it. In the next scene, Norman is seen entering his car, in the same outfit, and it is night time. (00:28:15)
The Convergence of the Twain - S5-E2
Continuity mistake: Norma's headstone gives a year of death as 2015. It also gives Norman's birth year as 1995, making him 20 when she died, but it is repeatedly stated that Norman is 18 when he enters Pine view, and Norma died 2 weeks later.
Suggested correction: Norma doesn't die 2 weeks after they move to Pineview, she dies roughly 2 years later. Dylan & Emma have a baby, then in later scenes a 2/3 year old child.
Pineview Institute is the mental hospital Norman enters (during season 4) and they say he's 18 and has to sign the consent forms. Then at the end of season 4, Norman kills his mother (Norma), which is about 2 weeks later. The city the Bates moved to is White Pine Bay. In season 5 (which is set 2 years after season 4 ends) every time we see Norma, it's Norman hallucinating as she's already dead.
She didn't die two weeks after she moved to white pine bay, she died two weeks after she got married to Alex.
Continuity mistake: When Norman is in Madeleine's shop, he picks up a chocolate chip cookie. We see him bite it, and we get a good look at the cookie. Then he sees Madeleine and begins talking to her. That is not the same cookie he had, because all of a sudden it has a huge chocolate chip near the top now...when it didn't before.