Factual error: When the plane takes off headed for Las Vegas, the shot out the window below shows runways 35 and 41. Runway 41 is impossible because ALL runways at airports are only numbered 1-36.
Factual error: Towards the end of the song "Out There" Quasimodo climbs onto the large spire on the roof. That spire was added in the 19th century and thus didn't exist when the movie was set.