Oh, where to begin...
My biggest - depictions of the military, especially uniforms. I'm not talking about ribbons being out of order or anything quite that anal. But, obvious things like hair being grossly out of regulations, wearing cover (headgear) indoors (when not under arms/armed), not wearing cover (headgear) outdoors, epaulets not underneath collars (sticking out), saluting during the wrong times and situations, and not saluting during the right times and situations...and my biggest: Not Saluting Correctly! Come-on, it's really not that hard. I've seen plenty of not-very bright recruits learn it just fine. If they can, anyone can. All it takes is a little bit of effort to get it right! But in the movies they'll invariably salute with splayed fingers, or the hand tilted with the palm outward, or the thumb sticking up, or the arm at some wrong/goofy/gawky angle, or any other number of screw-ups. Do your homework and get it right! Sheesh!
Then, there are writers and actors not doing their homework when it comes to technical aspects. Having been in aircraft maintenance for over 20 years, and my wife having been in nursing for most of her life; we both have a hard time watching anything involving aircraft or medical procedures.
The biggest aircraft movie discrepencies (IMO):
- Interceptor - Among the many, many, many problems with this movie, the worst is: the terrorists trying to steal an F117 from the cargo hold of a flying C-5 Galaxy, sneak aboard the C-5 during aerial refueling by crawling through the refueling boom. A boom which is only about 6 inches in diameter! I'm pretty sure the C-5 flightcrew would have noticed if the refueling boom they were connecting to was 4 feet in diameter, as opposed to 6 inches...
- Passenger 57 - A Federal Marshal (Wesley Snipes) sneaks into the avionics bay of a passenger jet and shorts a couple of wires out, causing the autopilot to turn the aircraft...and then later, basically does the same thing in order to make the aircraft dump fuel... - I've been in aircraft maintenance for over 20 years, and I did have a few wiring diagrams of a few systems on a couple of aircraft commited to memory, but a simple cop just happens to have memorized one specific wiring diagram from the dozens of different aircraft he may fly on, with the dozens of different wiring configurations and different manufacturers systems installed on those aircraft, and can short out wiring in a manner to cause a nice gentle turn (rather than a sudden hardover), and without any warnings being generated in the cockpit or the pilot intervening - Yeah, Okay! - Pull the other one!
- Diehard 2 - The terrorists crash an airplane attempting to land by reconfiguring altitude through the Glide Slope system - First off, Glide Slope does not transmit altitude. In fact, glideslope doesn't transmit data of any kind. It's a radio beam used to generate a directional steering command - period. Second - Altitude is determined on an aircraft in two different and independent ways: Barometric Altimeter and Radar Altimeter. Barometric Altimeters work off of outside air pressure, with purely mechanical sensing mechanisms, and they have absolutely no input from a ground station. The only way this could have been used by the terrorist, would have been to give the aircrew the incorrect barometric pressure (provided by an air traffic controller over the radio, along with things like windspeed and direction, temperature, conditions, etc.) - but then that leads us to the other altitude source. Radar Altimeters work by sending a radar wave at the ground from directly beneath the aircraft, and picking up the reflected signal with another antenna (also on the bottom of the aircraft), and determining altitude from how long the signal took to return. It's also independent of any ground station, and directly senses height above the ground, even in cases where the ground cannot be seen. They are typically set to give an alarm as certain altitudes are reached, and are used as the primary source of altitude during landing. Also a pilot would have definitely noticed any major disparity between the two indications (in which case they'd usually perform a go-around, or if they had to land due to fuel...as was the case in the movie...would have trusted the Radar Alt over the Baro Alt). The whole thing was completely impossible, yet a major plot point and mechanism of the movie, without which the plot falls apart. Disgustingly amateurish!
The final one that bugs me the most: inaccurate representations of firearms. Things like, people flying backwards after being struck by gunfire from common firearms (apparently Newtons 3rd law doesn't apply in movies!). If a projectile fired from a weapon had enough energy to send the target flying backwards, the person firing the weapon would also fly backwards in the opposite direction and the same distance! Also, targets of heavy military weapons responding as if they had just been hit by a common firearm. I've seen movies where the bad guys were shot by helicopter mounted mini guns or aircraft mounted cannons, and simply do the quick body arch followed by an agonized drop to the ground. In reality, a body struck by such weapons would virtually explode apart and practically disperse as a red mist! In most circumstances, if they would just switch around the effects they use for common firearms and heavy weapons, they'd almost have it right.
edit: was just watching an old episode of
Chuck and just had to add this: inaccurate representation of thermal imaging devices - specifically, showing them seeing through walls! Hell, thermal imaging can't even see through a window, let alone a wall!