Continuity mistake: When Sean shows up to meet with Mary Kate and her brother he is carrying pink roses. The entire time he is in the house the roses are now red.
Continuity mistake: During the extended fight scene, Will Danaher and Sean Thornton go crashing into a hay stack. As they emerge, they announce to the crowd that they are going to fight by the Marquis de Queensbury Rules. As they make the announcement, Sean Thornton's back is covered in hay. As he turns, the camera cuts to follow him, and there is instantly no hay on his back.
Continuity mistake: When John Wayne first meets with the woman at the church, the first time we see her she puts a dark piece of clothing over her head. In the next scene, which is a closer angle, it is gone.
Continuity mistake: Barry Fitzgerald meets with Maureen O'Hara as the shocklehorn (matchmaker). When they go into the house, it's a clear day. As they talk in the house, every time the camera turns to O'Hara, the window behind her shows a rainy day, but every other view out every other window shows a clear day.
Continuity mistake: When Wayne and O'Hara leave on the carriage with the horn, the door to the house is open. Cut to the wider shot and the door is closed.
Visible crew/equipment: Maureen O'Hara takes off her stockings and runs across the water toward the camera. As she gets closer, it's clear there is a light behind the camera as the camera casts a big shadow on her.
Revealing mistake: During the courting scene as they're riding through the countryside, the man controlling the horse has a pipe in his mouth. It casts a shadow on the rear-projected background, making it very obvious. So does Maureen O'Hara's hat. John Wayne's shoulder does as well.
Other mistake: Maureen O'Hara's brother punches John Wayne. You can tell how far away from him Wayne is, and the sound of the punch is a touch off. He's punching air.
