The marching band repeatedly casts long shadows/no shadows between shots.
When the family arrives in Merrivale, one of the kids is suddenly wearing sunglasses when he wasn't in the previous scene.
When they are driving the road to Merrivale, the dad is driving the car, but in the next scene when they arrive in Merrivale, the mom is driving.
At Miss Goldfinch's house, while singing "What's Inside It?", Miss Goldfinch suddenly throws the egg into the air...even though it was on the other side of the room (and not in her hands) an instant before.
While at Miss Goldfinch's house, Barney and his young friends are astounded to see the magical egg move and wriggle. However, minutes before they'd already seen the egg move and wriggle back in the barn when they first found it.
During the "Old Macdonald" song, At the very end where the animals are running, a Guy can be seen waving his hands around.