Harry Potter and the Half-Blood Prince (2009) - 10 major mistakes

Continuity: When Harry is kneeling beside Dumbledore's body, at the foot of the Astronomy Tower, Ginny joins Harry and holds him at his left side (viewer's right). In the last close-up of Professor Dumbledore's face, Harry is visible in the background with a space to his left and Ginny is now gone. That same angle was shown before Ginny joined Harry.

Visible crew/equipment: At the end of the Quidditch match, when Ron shouts, "Woo hoo!" with his arms raised, just as his cape flaps around the black seat on the actor's broom becomes visible. There are a couple of other quick glimpses of a seat during the Quidditch match.

Other: In quite a few shots during the film, it is much too obvious that there are no lenses in Harry's glasses, whereas in previous and following shots the glasses have lenses. A couple of instances are: when Harry drinks the Felix Felicis and when Harry kneels beside Dumbledore, at the foot of the Astronomy Tower.

Revealing: It is not what is seen here that is the problem, but what we don't see on the Hogwarts Express; first on the way to Hogwarts when Harry, Ron, and Hermione are in their compartment talking about Draco, and second, during holiday break, when Harry and Ron are talking about Unbreakable Vows. As the camera faces the large compartment window, we see the scenery out the window, but as the train speeds along, the scenic reflection of the windows opposite it, in the corridor, should be seen but isn't. What is reflected is the light colored wall of the compartment beneath the blacked-out window. The camera filming the shots from this angle is positioned at that window, and to hide the camera/crews' outline, the window was covered.

Continuity: When Hagrid and Slughorn are drinking after Aragog's funeral, Slughorn's cup is considerably larger than Hagrid's cup, but after Hagrid passes out Slughorn's cup is now the same size as Hagrid's cup.

Continuity: In the dormitory, when lovestruck Ron is going gaga over Romilda, he is wearing a brown sleeveless tee shirt and its tan trim has many holes. When Harry brings Ron to Slughorn, Ron is still wearing that tee shirt, but now some of the holes are gone and the rest of the holes have changed position.

Continuity: In Potions class, when Hermione stands before the cauldron explaining what she is smelling in her closeup, we see Neville behind her with the broad space to his right (viewer's left), just as she says, "Spearmint toothpaste". In the instant cut to the wideshot, Harry is now shoulder to shoulder with Neville, too fast for him to suddenly be standing that close to Neville.

Continuity: At the Three Broomsticks, after Slughorn spills the drink the foam on his fingers disappears, reappears, disappears, and so on.

Continuity: In the dormitory, when Harry walks in to see lovestruck Ron at the window, Romilda's card and empty chocolate wrappers are on Harry's bed. When Harry places the Marauders map and Potions book on the dresser, the card and wrappers have changed position.

Continuity: When Harry and Dumbledore return from the Horcrux cave, Dumbledore sits down with his arm around Harry's neck. When Dumbledore asks Harry to go fetch Snape, his arm suddenly disappears, and there was no time for him to have moved it.