Factual error: The six-wheel plastic G. I. Joe van that occurs beside some other toys in the Carvers' house was manufactured by Hasbro only in 1983. The film however takes place in 1973.
Continuity mistake: Right after Wendy is told to stop praying during the Hoods' Thanksgiving dinner, Elena picks up a plate of beets and serves herself one. Ben passes the rolls to Paul at which point Elena repeats the same thing (her plate is empty again). (00:45:10)
Factual error: The foliage in Paul's hometown is shown incorrectly in one scene. We are told that this is a suburb of New York City. We also know that it is around Thanksgiving, a time of year when the trees have shed their leaves for the winter. During the scene where Ben drives Paul home from the train station, all the trees in the background have their leaves.
Continuity mistake: When Paul gets off the train at the beginning of the film, the man who walks in front of him nearly slips on the ice. When the scene is flashbacked at the end of the film he walks safely.
Factual error: There are many errors in terms of location in the town, but you probably wouldn't notice unless you happen to know the town of New Canaan, CT. For instance, the sequence when Wendy is riding her bike makes no sense because the shots of where she rides down the main street are out of order. Also, as Wendy is talking to Sandy while on her bike you see a toy store in the background. That is actually a sports store that they covered up to look like a toy store.
Continuity mistake: Time of day in the last shot is incorrect. When the Carvers greet Paul getting off the train it is very bright late morning or noon at the latest. When the camera shows them walking toward their car the lighting has changed dramatically and you can see it is the late, late afternoon due to the dark orange hues.