Other mistake: When Aslan is resurrected, and the Stone Table cracks, you see Susan and Lucy stumble from the jolt and fall. If you watch closely, however, Susan prepares herself for the jolt before it ever happens. She throws her arms out and bends slightly at the waist, a few seconds before the jolt.
Other mistake: At beginning of the movie, where Lucy is leaving Mr Tumnus at the lamppost, she gives him her hanky. When the children come out of Mr Tumnus' house and meets the beaver, the beaver hands her the hanky she gave to Mr Tumnus. At the end after the children have been crowned. Lucy runs out on the balcony to see Aslan walking across the beach. Mr Tumnus comes out to comfort her. Mr Tumnus pulls the hanky, from under his scarf that she gave him when they met, despite it already having been returned to her.