Continuity mistake: When Harry puts his trunk on the pavement and sits down you can see him putting both hands to the ground. When it cuts while he is sitting down, you see him supporting himself on the trunk with his left hand. (00:07:10)
Continuity mistake: After leaving the Dursleys, Harry sits down on the pavement beside his trunk, with no room between the two. When he turns to look at the squeaking swings, in the shot from behind him, there is at least a foot of space between Harry and the trunk. Yet in the next shot that faces him, the trunk is beside him once again. (00:07:20)
Continuity mistake: When Potter spots the dog at the bus stop he stumbles backwards and falls onto the pavement. Then we see the bus light come at him. When it cuts we see the bus come around the corner. How could the light be shining on him when the bus wasn't coming at him at all? (00:07:50)
Continuity mistake: As the Knight Bus begins to appear, Harry falls back onto the ground, leans on his arms and in the front shot his sweatshirt is off his right shoulder, but in the next side shot, as he still leans on his arms, both sides of his jacket are properly on. (00:07:55)
Continuity mistake: After Harry leaves the Dursleys, Sirius the dog shows up behind a park bench surrounded by dimly lit thick bushes. When the Knight Bus arrives, the bench is visible across the street and now it's brightly lit and the trash container beside the bench is clearly visible. Then, before Harry boards he has one more look at the bench and it is just as dark as the first shot. (00:08:00)
Continuity mistake: When Harry falls backwards onto the pavement, after seeing Sirius the dog, in the shot facing Harry the trunk lies halfway up on the pavement. However, in the next shot as the Knight Bus nears, only the very top edge of the trunk leans on the pavement. Yet in following shots it is halfway up the pavement again. (00:08:10)
Continuity mistake: When Harry falls back after being startled by Sirius the dog, the Knight Bus headlights shine glaringly bright light all over Harry and the trunk. Yet in the next shot facing the oncoming Knight Bus, Harry and the trunk are barely lit by the headlights, which are nowhere near as bright. In the previous shot the light is obviously provided by spots. (00:08:10)
Continuity mistake: When Stan Shunpike begins, "Welcome to the Knight Bus emergency transport for the stranded witch or wizard...," in Harry's close-up the lamppost is directly behind Harry. However, in the shot from behind Stan when Harry says, "I fell over," the post is about 6 ft away, to Harry's left. (00:08:25)
Continuity mistake: When Harry gets on the Knight Bus, as he's stepping on, half of his jacket is wet (on the bottom) from falling on the wet pavement. Once he's on the bus, there's a quick shot of him from the back, and it is all dry. (00:08:40)
Continuity mistake: As Potter walks into the Knight Bus you see Stan lifting Potter's trunk inside. When it cuts, the way Stan comes in with the trunk changes. (00:08:45)
Continuity mistake: When Potter goes onto the bus he has his arms down. When in cuts he has his right arm in his pocket. (00:08:45)
Continuity mistake: When Potter has entered the Knight Bus you see him passing a bed. While doing so he grabs the bed pole and lets go of it, but when it cuts you can see him still holding the pole. (00:08:55)
Continuity mistake: When Harry boards the Knight Bus in the exterior shot, the curtain in the small window at the stairs is pushed open towards the outside of the bus. However, in the next interior shot the curtain is pushed open towards the inside of the bus. (00:09:00)
Continuity mistake: When Stan Shunpike says, "Take it away Ernie," we see Ernie having a bite of his toast. He then puts his hand with the toast down to put the bus in gear, but when the view cuts back the toast is suddenly gone. (00:09:20)
Continuity mistake: After Harry boards the Knight Bus, Stan hands him his ticket. In the shot facing Stan he folds the paper and holds it between his index and middle fingers. However, in the shot facing Harry, the paper is straight and he holds it between his thumb and index finger. (00:09:30)
Continuity mistake: On the Knight Bus, as Stan Shunpike holds the newspaper in his hands the position of the hat on his head changes in subsequent shots. (00:10:50)
Continuity mistake: As the Knight Bus stops outside the Leaky Cauldron we see Stan Shunpike fold the newspaper as Harry flies forward. When it cuts we see Stan Shunpike fold the newspaper again right before Harry hits the window. (00:11:40)
Continuity mistake: Just before the Knight Bus starts to squeeze between the two double decker's, watch the annoying Shrunken Head at the front of the bus. There's a long shot as the bus is just about to squeeze, and the head turns round to face Harry. There's a shot of Ernie pulling the leaver, then a close up of the head as it turns round again, and says, "Mind your head." (00:11:40)
Continuity mistake: When Harry enters the Leaky Cauldron you see Tom bowing while stretching his left hand out. When it cuts he is holding his left hand behind his back. (00:12:00)
Continuity mistake: When Tom and Potter arrive in the Minister's office Potter goes straight to Hedwig. When Tom says, "He arrived here just five minutes before yourself." you see Potter touch Hedwig's beak. When it cuts he is touching Hedwig's cheek. (00:12:30)
Answer: This didn't happen in the book. It appears to be done purely for comic effect in the movie, showing Dumbledore's eccentric and quirky nature. He's seemingly oblivious to what he's doing and how it affects Ron.
raywest ★