Continuity mistake: When Fred or George says "Sounds like the Irish has got their pride on", right before Arthur enter the tent, we see him swinging a pillow to his right ready to hit. When it cuts to Arthur entering, he has his pillow to his left. (00:09:50)
Continuity mistake: When Moody has turned Draco into a ferret, McGonagall shows up asking what he is doing. Behind her Harry is holding onto his bag's strap. His hand's position on the strap changes in the next shot.
Continuity mistake: When Voldemort says to Harry, "I'd introduce you, but rumor has it you're almost as famous as me these days," we see Harry resting his chin on the statue's sickle. When it cuts, he has his chin lifted from it.
Visible crew/equipment: When Hermione and Ron are in the library with Harry before the second task, Moody walks in to tell Hermione and Ron to go see McGonagall, and just as Ron puts the golden egg on the table the actor's blue tape mark can be seen on the floor. (01:29:30)
Other mistake: At the very end, the Durmstrang ship is leaving, it's away from the 'bank', firing its cannon. And then we see the Beauxbatons girls leaving Hogwarts... Followed by Durmstrang students whose boat has already left. (02:22:00)
Visible crew/equipment: After Fred and George drink the aging potion and jump within the "age line", right before they say, "Ready?" and drop their names into the goblet, at the start of this shot the actor's T-mark is briefly visible on the floor, just before one of the twins promptly steps to that area. A bit of a second T-mark is briefly seen as well, to its right, also where the other twin soon stands. (00:30:10)
Continuity mistake: Just as Harry flies back into the stadium during the first task, Fred and George's case is open in one shot and closed in the next. (01:00:00)
Audio problem: Just before the Death Eaters attack the tents, Arthur Weasley says to Fred and George that "Ginny is your responsibility", but his lips don't match what he is saying.
Visible crew/equipment: When the camera moves to look into Moody's "pit-like" suitcase, you can see the shadow of the camera on the left.
Visible crew/equipment: The camera is reflected in the metal water container when Dumbledore walks down the stairs to attend to Ron and Fleur's sister during the second task.
Visible crew/equipment: Just as Dumbledore reveals the Goblet of Fire, Barty Crouch Sr. is behind him. Just under his feet you can make out the edge of a white tape marker. (00:21:10)
Continuity mistake: When Barty Crouch Jr. lunges at Harry, Dumbledore grabs him and pulls him back. The camera does an instant cut and Dumbledore's grip on Harry has changed totally. (02:11:10)
Audio problem: When Fred and George mimic Arthur by saying, "Feet off the table" their lips don't move. (00:06:50)
Continuity mistake: When Mad-Eye tells Dumbledore and Fudge that Harry is outside the room, he opens the door with his wand and then proceeds to put it away. When the door opens from Harry's POV, Mad-Eye has still got his wand out. (01:37:50)
Continuity mistake: When Harry is deciding to ask Cho to the ball, he is in the doorway to the owlery. When he runs after her, he is in the owlery. No time has passed between the two shots. (01:09:40)
Audio problem: After showing the three unforgivable curses Moody comes down the stairs to Neville and says, "Son, are you alright? Come on, we'll have a cup of tea." However, when he says, "Come on" his mouth isn't moving.
Continuity mistake: During the scene in which the Tri Wizard cup is brought into the Great Hall and then Harry's name comes out of the Goblet of Fire, pay attention to Hagrid. We first see him move behind Snape and Moody who are in front of the window and standing directly behind them. Then he is further over to the right of the screen in front of the wall, and then back to his original position.
Continuity mistake: When Voldemort pushes Cedric's face with his foot, his foot's placement on Cedric's face change in the next shot.
Continuity mistake: When Harry falls into the Pensieve and sees Dumbledore, he leans towards him. In the next shot, he is noticeably further away.
Continuity mistake: When Harry returns with Cedric's body he says "He's back. Voldemort is back". When it cuts Dumbledore suddenly has got his hand behind Harry's head. It wasn't there in the previous shot.
Answer: Not at all. In fact, David Heyman made the decision for his eyes to be blue in the films for him to be more scary! They felt that his red eyes in Sorcerer's Stone did not show enough emotion to make him an evil character. It was felt in Goblet of Fire that the light blue eyes would be perfect to show his evil in the moonlight, and they kept it on for later films.