Factual error: When Clark speaks to Jor-El for the first time in the Fortress, Jor-El says "I will have been dead for many thousands of your years..." Fine in theory - Baby Kal-El travelled to Earth at above light speed so time passed differently for him. However, as such, wouldn't Jor-El have seen Earth as it was thousands of years ago? Which also makes there a problem with all the things Kal-El was taught during his voyage to Earth, as Jor-El references Einstein by name, for instance, and he would not have existed at the point when Jor-El sent him to Earth.
Factual error: The movie and events take place in 1958. However, two Fender amplifiers that are used by the band, "Johnny Casino and The Gamblers" are "Silverface" models that were only manufactured between 1967 and 1981.
Factual error: The car Flounder drives is a 1964 model, built beginning late in 1963, but the events of the movie take place in 1962. (00:45:40 - 01:08:25)
Factual error: The movie is set in New York. When Tony Smerko goes up on the roof of the studio to chop down the antenna, there's a green Art Deco building with a clock tower in the background - the Eastern Building, a downtown Los Angeles landmark since the 1930s.
Factual error: The credits roll closes with the caption "San Francisco...seven thousand miles away from Casablanca." San Francisco is less than 6,000 miles away from Casablanca. (00:03:20)