Continuity mistake: When Stuart is skateboarding in the birdbath the surface is smooth. Later when Margalo is in the bath with water the surface is in ridges.
Continuity mistake: At the start of the movie, Mrs Little scoops up baby Martha out of her cot and walks over to the bedroom window. She has the baby on her hip when she sits down at the window to see the birds but in the shot from outside the window, baby Martha is sitting on her mum's lap.
Continuity mistake: During the scene where the Littles are in the taxi looking for Stuart, Mrs. Little and George repeatedly switch places. (01:02:15 - 01:03:00)
Continuity mistake: At the soccer game, when the boy on George's team gets nailed in the gut with the ball, it rolls off his body. Yet, when they return to the shot of the boy lying on the ground, he is holding the ball. Who gave it back to him?
Continuity mistake: When Margalo is going out for "fresh air", her wing is still strapped with her scarf. As soon as she takes flight, Margalo's scarf is neat around her neck. I know that her wing isn't realy broken, but there was no time to untie it, unstrap it, put it around her neck and tie it, all while flying.
Continuity mistake: When Mr. Little and Mrs. Little are cuddling each other after arguing about overprotecting Stuart, Mr. and Mrs. Little swap places between shots.