Audio problem: When Ralphie's father opens the crate containing the leg lamp, he says, "Well, it could be anything." Then his mother says, "Maybe they forgot" without moving her lips. Obviously dubbed in later.
Audio problem: When the leg lamp breaks, it makes a crashing sound like breaking glass, but then the wife asks "Why would I be jealous of a plastic lamp?" and it's obvious that the lamp is indeed soft plastic.