Factual error: When Magneto enters RFK stadium, a groundskeeper is lining a baseball field. RFK stadium did not host baseball in 1973, as the Washington Senators had moved to Texas to become the Texas Rangers after the 1971 season. In 1973, the only team playing in RFK regularly was the Washington Redskins of the NFL. In addition, the Paris Peace Accords were signed in January of 1973; so there wouldn't be green grass inside the stadium, regardless of what sports were being played there.
Factual error: Towards the end of the film, Spiderman takes his web and uses it to connect to the different power conduits that Electro blew open, ties them together, and power the city back up. Electricity uses several different wires, and crossing them would cause things to blow up or short out. What should have happened when Gwen threw the switch was another power failure, instead of the city's power being restored.
Factual error: When Vlad goes into the Master Vampire's lair a second time, a Golden Knee Tarantula can be seen. These types of spiders are native to the Chaco region of Argentina, South America. Not in Eastern Europe.
Factual error: In the rat revival scene, Dr. Terra Wade, an electrophysiologist, demands that the other scientist, Dr. Bell increase the current, going as high as 200 joules. However, current is measured in amperes (amps), joules is a unit of energy.
Factual error: During his final debate with Professor Radisson, Josh states that science supports the existence of God. There is no scientific evidence to support the existence of any god from any religion. This line is made all the more dubious given that the film earlier made reference to the works and writings of Richard Dawkins and Stephen Hawking - who are two of the most respected scientists on the planet and neither of whom are theists - as counterpoints to his decidedly unscientific claims in earlier debates.