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: Jake takes a huge piece of gold and condenses it down into a small strip. It is then lifted with no difficulty. For the science of the film to work, this would have to be done without losing any of the gold's mass, or they could just get a small piece. As of such, the condensed gold would be just as heavy, if not heavier than in its original form.
Factual error: When Rita is in the doctor's surgery for her prenatal visit, the chest X-ray in the background is upside down.
Factual error: When they drain the pool at the abandoned army station, Paul tastes the water and claims the water is salty. Piranha are freshwater fish and would not survive in salt water. (00:19:30)
Factual error: It was mentioned the museum has $3 million in gold bars. At 1978 prices, that is about 280 pounds. Gold is fairly heavy and the size of the bar shown in the film looks like 25 pounds. Assuming about 25 pounds per bar, I counted 134 bars or 3,350 pounds or almost $36 million dollars. I guess a big stack of gold bar looks better than a small stack of 11 bars. (00:41:55)