Other mistake: After Carl and Russell meet with Cumulonimbus cloud Carl takes a nap and we find that Russell wakes him up, after that we see that Carl goes and peeps out of the window he places his walking stick near to him and facing him, the next to next shot we see that its moved and is facing opposite to him. even though the camera is moved a bit its not possible for the stick to rotate so much and moved.
Other mistake: Shortly after the house takes off for the first time, in a scene where part of the city can be seen that includes various buildings and houses, the shadow of Carl's house and the balloons can be seen on the ground. At first glance it looks OK, but the angle of the shadows of objects on the ground is completely different from the shadow projected by the house. The buildings on the ground are projecting a shadow to the left, indicating that the sun is low to the right. However Carl's house shadow indicates a light source from behind the camera which is about perpendicular to the shadows on the ground. To be technically correct in this shot, all shadows must point away from the camera and the sun should be located behind the camera if the house's shadow is to be seen in the shot.