Factual error: During the scene on the Helicarrier where Bruce Banner "Hulks out" and jumps at the F-35B hovering just outside, we see the F-35B fire its guns, one inside each of its intakes. The F-35B has only one gun, externally mounted to underside of the fuselage. It would be impossible to mount a gun inside an aircraft's intakes.
Factual error: The Mark 7 takes 9 seconds to assemble - give or take. Judging by the view of the Chrysler Building, Stark Tower is about 300 meters high. Even if you wouldn't count the time it takes for the suit to catch up with Tony, 9 seconds is too long, he would hit the ground before the suit would fully assemble.
Factual error: In the scene in Stuttgart, we see a "reserved parking" sign written as "Reservierten Parken". First of all, this is grammatically wrong - if used at all, it should be "Reserviertes Parken". But you wouldn't find a sign in Germany saying that. They say "Reservierter Parkplatz".
Factual error: When Natasha/Black Widow jumps off of Captain America's shield and grabs onto that flying device, it was going so fast that it would have ripped her arms off.