(NOTE: One plot point will be revealed in this post, but no major spoilers. But, given that this is a mindless action movie, there isn't much to spoil. You probably already know how it's going to end.)
I've actually never seen any of the Die Hard films, so I came in with extremely low expectations. I wasn't disappointed. There was plenty of senseless violence and mayhem, and probably a fair share of physics-defying stunts. But, I'm not a physicist, so I will focus on the two things that I did recognize as scientifically incorrect.
The first was after a long fight when Jack McClane (the son of John McClane, who is Bruce Willis' character) was injured. A piece of metal had pierced his side, and his father mocked him by asking (paraphrased), "When did you get your last tetanus shot?"
This is a common misconception. Tetanus is not caused by rusty nails; instead, it is caused by a soil-dwelling bacterium, Clostridium tetani. This anaerobic bacterium also forms spores, and these spores are readily found in the soil. What else can be found in the soil? Rusty nails. If you step on a rusty nail that is contaminated with soil, there is a very good chance that you just inoculated your foot with Clostridium spores. As an anaerobe, Clostridium can't grow in healthy tissue (due to oxygen), but injured tissue provides a suitable environment. As it grows, it releases a potent toxin that causes tetanus, which manifests as uncontrollable muscle spasms and contractions and even asphyxiation.
So, technically, the movie wasn't "wrong" to mention tetanus in conjunction with a wound (since Clostridium can enter the body through any wound), but John McClane perpetuated a widespread misconception by not providing a more detailed explanation of the underlying microbiology to his injured son. We'll call it an error of omission.
The second error that caught my attention was far worse. Our heroic team heads to Chernobyl, and one of the characters whips out a device that reminded me of the proton pack from the movie Ghostbusters. The character used it to "neutralize" the radiation.
Radioactivity cannot be neutralized. That's one of the reasons why radioactive waste is such a menace. Not only is it toxic, but some radioactive isotopes last a really long time, and there isn't anything we can do about it except wait until they decay. Depending on the isotope, that could take anywhere from fractions of a second to billions of years. The long half-lives of some radioactive isotopes is why we build long-term storage facilities, such as Yucca Mountain (which the Obama administration shut down for political reasons in 2009).
Overall, the film was enjoyable in that it fulfilled my testosterone-fueled need to see explosions and car crashes. But, two of my friends -- both of whom were fans of the Die Hard series -- hated it.
(Image: Movie poster for 'A Good Day to Die Hard' via Wikimedia Commons)