Movie fans love spotting mistakes in films. In between takes of a scene, time goes by.  That cup that was on Hermione's left suddenly is on the right. Or the person who was sitting next to Ron in class is suddenly not there. Maybe they mess up and a cameraman inadvertently appears in a scene. Or you spot the microphone that isn't quite tucked into Aunt Petunia's shirt.

Every film has continuity errors. The start and stop and start again nature of films makes that inevitable. So, let's have a look at the Harry Potter films and see what we can come up with. Here are 10 continuity errors fans probably didn't notice in the Harry Potter films.

10/10 Chamber Of Secrets - The Weasleys' Clock

Harry Potter Weasley Clock

Harry visits the Weasleys' magical home the Burrows for the first time inHarry Potter and the Chamber of Secrets. The family has this clock on the wall that shows where family members are or should be. In a close up you can see an option for going to the dentist. All well and good.

But inHarry Potter and the Half-Blood PrinceHermione has to explain to Professor Slughorn's Slug Club what a dentist actually does, because they don't exist in the wizarding world. Slughorn innocently asks her if it's a dangerous profession. She replies that it isn't, but that a little boy bit her father once. Nobody gets the joke.

9/10 Half-Blood Prince - Ron Foaming Or Not Foaming At The Mouth

Professor Slughorn has returned to Hogwarts to teach Potions. He's a bit of a snob, but harmless enough. At one point, Romilda Vane leaves a box of chocolates, laced with a love potion, for Harry. But food-greedy Ron gets to them first and ends up lovesick in the extreme. Harry hurries him off to Professor Slughorn for a curative potion. Only thing is, poor Ron ends the session by drinking poison.

As he flops around on the floor he is sometimes foaming at the mouth and sometimes not, depending on the shot. Harry saves the day as poor old Slughorn loses it.

8/10 Chamber Of Secrets - See You At Work

Lucius Malfoy was never known for his warm and cozy behavior. From the beginning, he is arrogant and dismissive of the Weasleys with their red hair and hand-me-downs.  In the first half-hour of the film, Malfoy and Weasley meet while at Flourish and Blotts in Diagon Ally.

The two trade insults, with a smiling Arthur holding his own. If looks could kill is all that can be said about Hermoine in that scene. As Lucius prepares to leave, he tells Arthur that he will see him at work. Of course, Arthur works at the Ministry of Magic. Only thing is, Lucius doesn't. Whoops.

7/10 Deathly Hallows Part I - Drawing Of Deathly Hallows

Xenophilius Lovegood, Luna's father, is up to no good. But Harry, Ron, and Hermione don't quite realize it yet. He is explaining the Deathly Hallows and does a drawing to illustrate. His hands, together with the paper on which he is drawing, are covered in ink smudges in one shot.

Then when he starts talking to Harry and the camera refocuses, the smudges have completely disappeared. Then in the next shot, they are back again. The scene was shot in a number of takes and things just got confused.

6/10 Sorcerer's Stone - Harry On Both Sides Of The Table

In the early days when the production company was shootingHarry Potter and the Sorcerer's Stone, it was exciting, but everyone was new to what would become a runaway hit of a franchise and quite a few mistakes happened. Case in point:  in a scene shot in the dining hall during a feast, Harry is first seen sitting on the right-hand side of the table across from Hermione.

In the next shot (with no time elapsing) he is on the left sitting next to Hermione. In between takes of this scene, a continuity person wassupposed to make certain everything was the same. But with so many details to keep up with, it can be difficult.

5/10 Goblet Of Fire - Professor Lupin's Class

TheGoblet of Fireis all about the Triwizard Tournament and the return of Voldemort. It is also about Alastor "Mad-Eye" Moody (or who they think is Moody) coming to Hogwarts to teach Defence Against the Dark Arts. Well, after his first spectacular class, Hermione and Harry are leaving.

Behind them, an extra can clearly be heard saying that she had Professor Lupin's class next. Only thing was, Lupin famously left at the end of thePrisoner of Azkabanand is no longer at Hogwarts. Or maybe he's hiding in a cupboard somewhere?

4/10 Chamber of Secrets - Film Crew Visible

When Gilderoy Lockhart (Kenneth Branaugh) signs on to teach Defence Against the Dark Arts, there are many comic moments. Kenneth Branaugh gives the character an arrogant charm that is good for a laugh or two. But things turn sinister when Harry and Malfoy face off for a duel, wands at the ready.

Harry prevails and when Professor Snape comes to haul a flat-on-the-floor Malfoy up, a cameraman can clearly be seen filming behind the row students.

3/10 Prisoner Of Azkaban - Broken Pot

While Ron cools his injured leg in hospital, Harry and Hermione use a Time-Turner and go back in time to rescue Sirius Black and Buckbeak. Escaped prisoner Black has been captured and Buckbeak is under a death warrant. So, the exact same events play out twice. As Harry and Hermione hide behind Hagrid's cottage, Hermione throws a rock that shatters a vase on a table.

Only thing is that in one shot (of the past) it's shattered into little pieces and in the other shot only a piece has been broken off. It should have been the same.

2/10 Deathly Hallows Part II - James/Sirius Robes

In a flashback sequence inDeathly Hallows Part II, first-year students James Potter, Lily Evans, and Sirius Black are sorted into Gryffindor. Lily goes last. When she goes and joins James and Sirius on the benches at the table, you can clearly see that both boys are wearing Gryffindor robes and ties.

They should have been in the same plain black robes as Lily, as they have only just been sorted into Gryffindor. They probably had changed to shoot a different scene, thinking nobody would notice.

1/10 Order Of The Phoenix - Hermione's Feet

Harry, Ron, and Hermione are interacting with Grawp, Hagrid's little brother. He's not what you would call attractive or very smart. Grawp decides to pick Hermione up (against her wishes, we might add). Now Grawp and much of the scene is done using green screens and CGI (Computer Generated Images).

And in one shot, it is clear that the digitizers messed up, as they have done the break wrong and erased Hermione's feet. Things like this are bound to happen. And when they got around to editing the scene, it would not have been practical to reshoot it.

NEXT: Harry Potter: 10 Reasons Harry And Ron Aren't Real Friends