Continuity mistake: When the girl gives Litwak her phone to show him there is a replacement part on eBay, her phones shows that it is connected to WiFi. Litwak doesn't set up his router until later that evening, he has only plugged it in. (00:09:41)
Suggested correction: It's possible she's either connected to wifi at another nearby business, using a public wifi signal, or using a friend's phone as a hotspot.
Continuity mistake: When Kate is hanging on to the sleigh as it takes off she is holding on with one hand. Camera changes and now she is holding on with both.
Continuity mistake: Meg starts the trip wearing a red flannel shirt over a blue cardigan over a gray T-shirt. Along the way she first drops the flannel shirt, then the cardigan (the color of which seemed to have gained saturation). She's not seen carrying them or any bag that might have held them. When she finally faces It, all the clothes are back on. Calvin's case is even more evident: he starts with a jacket over a red shirt, ends up with a just a now-gray T-shirt (matching Meg's) but is back with jacket and red shirt at the end.
Continuity mistake: As Keda is tumbling down the face of the cliff, he smacks against a small ledge on his way down before hitting a second ledge and then landing on a third. But as the camera goes down the face of the cliff from the top of it, the two ledges he hit on the way down are gone, showing a mostly flat face. (00:28:20)
Continuity mistake: When the movie begins the smallest boy holds a neat pile of towels. When the shot changes they're messed up. Then they swap back to neat. (00:08:15)
Continuity mistake: Towards the end after all the monsters are gone, in the background the sun is barely shining, but after 5 or 6 minutes when Sarah and the others are outside the building it's completely daytime.
Continuity mistake: After Dumbledore gives Newt the card for the safe house in Paris, they teleport to a bridge where they continue talking. Dumbledore then tells Newt why he likes him so much, and in the side shots, Newt is shown holding the card up. When it cuts to angles from behind Dumbledore's shoulders, his arm and hand are much lower with the card and his head turned in a different position. (00:20:35)
Continuity mistake: When the robber is arrested, his hands are cuffed behind his back. When he's being loaded into the police car, his hands are suddenly cuffed in front of his body.
Continuity mistake: In the opening scene with the skype call, Mia's hair is in front/behind her shoulders depending on the camera angle, with no logic. (00:00:55)
Continuity mistake: Princess Dawn is in her chambers and her servants are preparing her for the coronation. When her book-headed valet tells her "You have come of age", he is suddenly holding the tome with both hands, while he had just one on it before the cut. (00:19:30)
Continuity mistake: Sparse snowflakes fall in wide shots, but there is heavier snowfall in close-ups of Barbi. (00:29:30 - 00:30:15)
Continuity mistake: When Captain opens the bridge gate he puts his right hand to his chest. From the opposite shot it's down.
Continuity mistake: When Bart's dad asks how he got such a beautiful girl, he looks at Bart. The shot cuts to behind him and suddenly he's looking at Shannon again.