Eraser

The film "Eraser" details the story of a Witness protection agent named John Kruger, player by Arnold Schwarzenegger, who fakes the death of the people he is assigned to protect and gives them fake identities to keep them safe from those who are trying to harm them. This is how he earned to nickname "the Eraser." After he learns about the illegal arms sale of handheld rail guns, he does everything he can to stop take down the sale and find who is responsible.

In the scene above, Kruger picks up the rail guns that were supposed to be sold to a terrorist organization and used it against them. While Arnold holding two rail guns firing them at the same time is a cool scene and an awesome action piece, one has to wonder, "Could Arnold Schwarzenegger even hold and fire those guns?"

In the film they say that the rail gun fires projectiles "the speed of light", which in it self is impossible due to the theory of general relativity. Assuming that the projectiles could move at a velocity equal to the speed of light and that the projectiles have an equal mass to the standard 5.56 bullet (62 grams), we could calculate the momentum at which the bullet has and how that momentum affects the shooter (Arnold Schwarzenegger). The momentum of the bullet should be the same magnitude but opposite direction of Kruger's momentum.

mv = rail gun
mv = Kruger

mv = mv
(.062 kg)(3 * 10^8 m/s) = 114 kg * v
1.86 * 10^7 kgm/s = 114 kg * v
v = 163,158 m/s

As shown in the equation above, after firing the rail gun, John Kruger should fly backwards at a velocity of over 160,000 m/s which is over 14 times faster than the escape velocity of earth.

In conclusion, not only would it be physically impossible for a hand held battery to produce enough energy to accelerate an object to the speed of light, but firing such rail gun that could would destroy anything that tried to fire it, and Kruger was shooting two at the same time. Due to these facts I give Eraser an NR rating. There is a blatant disregard for physical principles and concepts with the rail guns in the movie.