Factual error: The sisters run out of fuel for the helicopter, which is then shown slamming down on the ground and essentially destroying itself. All helicopters are capable of autorotating safely to the ground in the event the engine(s) quit. Of course, that would not have been as dramatic. (01:05:15)
Factual error: Melina tells Natasha that the only way to get past Dreykov's pheromone block is to sever her olfactory nerve. So Natasha smacks her head on a table to sever it, hits Dreykov, then later pops her apparently broken nose back into place. Not only was her nose visibly not broken, but the olfactory nerve is a direct extension of the brain, with projections passing through a key bone in the skull. Severing that nerve would involve brain damage, and traumatic damage to those structures capable of this would require surgical repair.
Factual error: When she looks at the football game in 1995, the referees are wearing black pants. Those pants were not used until the 2010s.