Steven's jacket and shirt change when he enters the magic store at the beginning of the movie, then change back after he exits.
When Steven and Lorena dance at the wedding, the same red-haired woman is led across the dance floor twice.
When Lorena is watching the videotape made of Steven apologizing to her for the message he left on her entrance door, you see her expression in several cutaways. The background showing her dining room to the right is always lit except for one cutaway in which the dining room is pitch black.
When Stephen brings home the dummy for the first time, he only opens the latch on the left side of the suitcase first. In the next shot, he opens both of the latches, even though the left would have already been unlatched.
When Steven is driving Fangora home she flicks her cigarette butt out the window as he pulls over to the curb. When they are in the car talking she is not smoking but when she gets out of the car she is smoking again.
When Steven is driving around, the car is clearly in park.
Heidi's and Fangora's singing at the wedding.
Steven returns the dummy to the magic shop where he bought it. However, when he leaves the shop, a sign reading "All sales final" can be seen on the door behind him.