Factual error: When Sherrie and Drew are in Tower Records, the background song is I Remember You by Skid Row. But that album wasn't released until 1989, and the movie is set in 1987.
Suggested correction: The movie also says that Drew wrote "Don't Stop Believin" when the song came out in 1981. They also sing Heaven and More than words which didn't come out until 1989 and 1990 respectively. It's a musical that's full of 80's music, so they pulled all sorts of 80's music. It's not a mistake to have songs show up in a year, in a completely made up timeline.
Factual error: At the beginning of the film, Pat's Mother picks him up in Baltimore to return to Philly. In the scene from the car as they pass the Linc, the stadium is on the right, indicating that they are in fact traveling South on 95 towards Baltimore. Additionally, the previous scene of the city from the car could not have been shot from 95.
Factual error: The VW Bug that the belfry falls on is a later model than 1965 when the movie is set. The larger tail light with yellow on the lens seen on the VW in the movie didn't come along until 1968. The one in the movie may even be of early 70's vintage.
Factual error: When Bella is driving back from Seattle, the speed limit signs say 80. There is no 80mph speed limit road between Seattle and Forks; the movie was filmed in Vancouver and the sign is, in fact, in kph. (01:04:55)
Factual error: At the beginning when Heinrich's brother falls from the building there are two mistakes that can be seen. First: The cars are driving on the wrong side of the road. Hong Kong drives on the left just as they do in England. Second: The license plates on the cars are for Mainland China, not for Hong Kong. China uses blue background with white letters, while Hong Kong uses yellow or white with black letters.
Factual error: In one scene Drew Barrymore stands in from of a political world map, showing the political borders as of today. You can see the successor countries of the Soviet Union in that map. But the plot plays back in 1988, with the Soviet Union still alive.
Factual error: Whenever Charlie, Patrick, and Sam go through the tunnel into the city, you can see "Consol Center" on the road sign. The Pittsburgh Consol Center was built in 2008, but this movie's set in the 90s.